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Resource recommendations for teaching OOP via a practice-oriented example I intend to teach some OOP methodology but everywhere I look, there are only syntethic examples and elaborations of various concepts of the OOP world (for example: what is inheritance, how to use interfaces). Like this or this . What I'm looking for is a tutorial of how to solve a "real-world" problem (can be fictious) but with all (or most of) the steps of these: How to analyze the problem? What are the objects? What should be taken care of? What classes should be created? What pattern is recommended? I found a good book online but it is way too detailed to be a quick guidance - though not a bad start. Nevertheless, I'm looking for a shorter and more practice-oriented approach. As you can see, I'd like to have a tutorial that teaches OOP as a whole and not its parts. The students are mostly beginners but trying to use a wide range of OOP concepts - they have a few months of experience. Do you know any example that has this kind of tutorial structure ? <Q> I'm currently teaching OOP using Python 3 Object-oriented Programming by Dusty Philips. <S> Find it on Packt or Amazon. <S> It's a practitioners book, it covers a bit more than just OOP including some unnecessary bits if you ask me (like concurrency). <S> I've found it works out well when combined with a few other sources like Effective Python and some online materials on design patterns. <S> If you follow it page by page I find it a bit too much focussed on Python details and not as much on the general OOP principles. <S> I think that in most cases you'll have to make up your own curriculum and fill it with bits and pieces from books you like :) <S> There is rarely a perfect fit. <A> The best book I know that follows fairly closely to this format is Polymorphism: <S> As It Is Played , which observes two students slowly build out a calculator. <S> True to form, the book takes the reader deeply into the mindset and core philosophy of OO. <S> It's a quick read with very short pages; it took me a few hours. <S> The book also explores some important areas of the software development process. <S> Paired programming, which runs through the entire book, works well in the classroom (there are many questions about it here on this site), and aspects of Agile development are also explored. <A> There is “A touch of class” by Bertrand Myers. <S> It is a very good book, at least a semester worth of learning in it. <S> I did not get OO, until I read it. <S> I had previously done C++, java, C#, and some python. <S> But when I read this book, I started to program OO properly. <S> The book uses a language called Eiffel. <S> It is a good teaching language, and also used in large systems, safety and mission critical systems. <S> It is probably quicker to learn Eiffel then another language (or two), than try to learn other OO languages from scratch. <S> (This is the authors clame, and my experience as a learner) <A> It is not deep enough but could be used as a starting point. <S> I leave the question open for the time being as it can have more suggestions. <S> Please feel free to add more and more resources. <A> Introduction to Programming with Greenfoot by Michael Kölling might be what you want. <S> Michael has a great grasp of OO and has built a great tool (Greenfoot) for beginners to explore it. <S> The book has a number of simulations that are used to develop Java programming with OO principles integrated. <S> The first four chapters (especially) of Karel J Robot by Bergin, Stehlik, Roberts, and Pattis also present OO principles in a simulation context, but also using a few simple design patterns. <S> The Karel book has analogues for Python and Ruby also. <S> Karel can be used within Greenfoot if desired or in other IDEs. <S> These are also simulations and show interesting objects moving and interacting on the screen (the World). <S> New worlds can be created (inheritance) and new Actors as well. <S> It is easy to integrate design patterns into the curriculum with these tools since the supplied software infrastructure means that the student isn't starting with an empty screen but with a well defined framework in which to develop the ideas. <S> So, the student starts at a higher level of abstraction than the language primitives. <S> Classes, methods, interactions, composition, delegation, etc. are natural topics that can be explored early in the student's learning.
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I found a book online ( Object Oriented Programming using C# by Simon Kendal ), and it has an example of designing a simple administration system using OOP principles ( Chapter 6: Object Oriented Software Analysis and Design ). There is a teacher resource for Greenfoot ( https://greenroom.greenfoot.org ) that has many projects for use within the greenfoot system.
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Single-dimensional array and simple looping activities of significance I give a lab on single-dimensional loops and arrays. By "single dimensional loops", I mean that there is no nesting of loops. (I will later give a second lab on multi-dimensional loops and arrays, but that is not this lab.) The problem is that few of the problems on my lab right now are of any consequence. What I want is to provide activities that are significant in computer science. These students are still early enough that I'm not requiring nested loops, but that doesn't mean that they can't be exposed to significant ideas. The trouble is, what are those ideas? Good activities would either be algorithms of significance, or they will set the stage for later comprehension of deep and important ideas in CS. What are lab activities that can be done without nested loops that reflect important problems in Computer Science? <Q> The Dutch National Flag problem is linear in running time. <S> Essentially sort an array with only 3 distinct values each of which may appear 0 or more times. <S> (not length 3). <S> You are allowed only one pass over the array, so the solution is a single while loop with some prior initialization. <S> It was probably originally posed by Dijkstra. <S> It is mentioned in David Grits's The Science of Programming where it can be solved very nicely by posing pre and post conditions using David's ideas of finding invariants from pre and post conditions. <S> You can also make it a simple object oriented problem if you like by using objects as the array elements, for example. <S> A more interesting formulation of the problem refers to the Dutch National Flag which is a Tricolor: <S> Red over White over Blue. <S> You have an array that has some jumbled up red and white and blue cells, zero or more of each. <S> You want to move all of the red cells to the left end, all of the blue cells to the right end, with the white cells in the middle. <S> The restriction is that you may make only a single pass over the array. <S> The correct solution is very creative and demonstrates the power of loop invariants. <S> I have mentioned this problem in answers to other questions here. <S> A search for "dutch" on the questions page will reveal them. <S> Solving it without hints can provide a gigantic a-ha moment for almost everyone. <S> If students can do the classic version, they can also think about a modification that will handle 4 values instead. <S> From that you can talk about the inherent complexity of sorting values from any finite set. <A> A variant on the ENIGMA machine encryption works well in a single loop, and is sufficiently complex to give students a real challenge. <S> The core idea of the ENIGMA machine for this assignment is that (1) a number is given as an initial key, and (2) <S> every prior letter used influences how the next letter will be encrypted. <S> So, use a modular circle of encryptable characters (I chose ASCII 32 ( ) to 126 ( ~ ), and just like a Caesar cipher, take your first letter and move it over by the key values. <S> But now modify <S> key itself by adding the ASCII value of the inputted letter that you just encrypted to it. <S> Unstated in that description is the idea of creating a modular circle that doesn't begin from 0. <S> This is a pretty complex idea for students at this level to work with, and it helps to give them some guidance in this department. <S> Following this formula with the initial key 16 , the statement Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal. <S> Should get you: Vf|0Pdhx,2RTch)=CZ`o0JPRey:<DTt%;Nnuw-6<Oc$':J`hq'GN^q'0P`o0ENXl-1APeo~%4Iu68Xgm&FUWlv'6b#'7FJPZqw|=GVvcmpv*?Y&FHW\|"(-7;=RX]}3Ccx"(HYl|.>R\q{,;[py{1QS`m.<BQqs'-MQdjl"(-MSe{}+Y <S> Ask students to similarly create a decrypt method, but offer far less guidance than you did for encrypt. <S> It will require them to make sense of all of the mathematical operations that they performed in encrypt in order to successfully undo it. <S> You can also provide them with a few mystery strings to uncover. <S> The first student who successfully follows the directions given by the mystery strings gets some sort of prize or extra credit. <S> (The mystery strings themselves explain this; no need to give the secret away in advance.) <A> You could use introduce elementary (one-dimensional) cellular automata . <S> Basically, you represent a single row of cells as a simple array. <S> Then you write a function that takes an array and applies the rules of the cellular automata to each cell (usually based on the old value of the cell and its two neighbors) to return a new array representing the next generation. <S> It's dead simple, but still results in pretty cool patterns if you display (or just print to console) <S> the generations one after another. <S> Here are some examples: <A> Grades. <S> Works especially well around final exam time. <S> You can find the average. <S> Find the highest and lowest. <S> Find the average with the lowest dropped. <S> Find the most common grade. <S> Count how many are in the range 90-100%. <S> Given an array of grades assigned for each class, calculate GPA. <S> Given 3 arrays that represent labs, quizzes, and tests <S> calculate the final average. <S> Each array can be weighted differently to match whatever your grading scale is. <S> Ex: I would have labs weighted at 10%, quizzes at 20% and tests at 70%. <A> I recommend to check out <algorithm> , <numeric> , and related C++ headers. <S> There are literally tons of linear algorithms of utter significance. <S> From the top of my head, copy , reverse , find , lower_bound , accumulate , iota , partial_sum , adjacent_difference , inner_product are well deserving much attention. <A> The irrational number $e$, also called Euler’s number, is approximately 2.71828 . <S> The number is significant both to the culture of computing and has a role in such functions as computing continually compounding interest. <S> Euler proved that this number was irrational by showing that it was equal to the infinitely expanding series $1 + \frac{1}{1} + \frac{1}{2!} <S> + \frac{1}{3!} <S> + \frac{1}{4!}$… Ask students, then, to create a function that, given a number of iterations, returns the approximation of $e$ given by that many steps.
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One small, but significant, algorithm is to find Euler's Number.
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Quick and easy intro to computer science for kids for an Engineering Field Day We have a large engineering day that hundreds of kids (ages 6-12) and their parents will attend. The setup is as follows: local engineering groups/societies will have stations and they will have short activities for these kids to introduce them to engineering concepts. We are looking for 1-2 activities for one of these stations. There will be internet connection and we have a small budget (~ $100 ) for getting supplies. We can borrow computers/tablets. Ideally we will have two activities that build on each other and ideally the activities can be scaled so both younger crowds and older students can enjoy and get hooked. It would be a big plus to engage and educate parents as well. It would also be a plus if the activity did not require lots of hardware ($$$) so it is not too hard for students to continue learning at home. I wanted to do something programming/CS related but I am having a hard time coming up with activities that introduce them to the subject in a couple of minutes . Are there such activities or should I focus on something else? The help and ideas are much appreciated! <Q> Since Logo was intended for this age group you might explore something there. <S> My quick idea would require two or three screens with some sophisticated and time consuming simulation running on one and the kids/adults exploring simpler exercises that might (or not) build up to the one running. <S> You can run, for example, a space filler (Sierpinski) program and have the students explore turning, etc. <S> With lots of trial and mostly error. <S> In Karel J Robot, the recursive graphical solution to the Eight Queens problem takes a bit of time and is built up from only a few primitives that can be combined and extended. <S> So that would do for the running demo and the students can explore simpler aspects, such as a robot backing up, for example. <S> The advantage of Eight Queens is that it is easy to explain, unlike, say, sorting. <S> You can do this sort of thing in most languages - a complex graphic simulation built up from simple parts. <S> The students explore only a bit of it. <S> They can even modify some of the code of the running sim and run it to see what happens. <S> It can lead to a lot of laughter, and some insight. <S> If you sit with them you can suggest things that do something fun/weird/good/bad and ask why that happened. <S> Lots of possibilities. <S> But the running sim gives an unattainable target in the time frame. <S> Like playing on the beach after professional teams of sand-castle builders have shown their skill. <S> The suggestion is that if the simulation is built with something like Model-View-Controller that the students only modify parts of the model. <A> There is another model program that is designed for youngsters. <S> CSUnplugged <S> provides a collection of activities that don't involve actual computers but prepare young students for Computational Thinking and algorithmics. <S> Some of the examples are surprisingly sophisticated and collectively cover, if somewhat shallowly, the range of topics that would later be covered by in a college major in CS. <S> Each of the (more than 30) activities they suggest are accompanied with teacher instructions. <S> These activities have been successfully used in a number of elementary schools. <S> In my opinion, they provide a great way to instill insight into youngsters in topics that they might study later in depth, but which they will also necessarily encounter throughout their lives. <S> For your Engineering Day you could prepare a few of these for the students to do. <S> Some of the resources are also group activities, so that you might get a larger group engaged simultaneously. <S> The same materials, by the way, can be adapted for teaching the underlying concepts to adults, by providing a set of analogies and metaphors for the topics being studied. <S> They might also provide ideas for programming exercises for beginning students in a CS program. <S> The main categories follow, with several activities available for each: Data: Representing Information Algorithms: Putting Computers to Work Procedures: Telling Computers What to Do Intractability: <S> Really Hard Problems <S> Cryptography: <S> Sharing Secrets <S> The Human Face of Computing: Interacting with Computers Community Activities <S> One of my doctoral students explored this area in her dissertation and found it to be valuable. <A> I created a couple of demo programs recently which can run unattended, be explained simply, are familiar, and one can be interacted with. <S> The first is a simple maze generation method, which draws a maze on the screen with character graphics. <S> It does not produce ideal or optimal mazes, or use any of the recognized algorithms, just weighted random choice and forcing. <S> Still, it is interesting to watch. <S> I have not completed the part that displays the shortest path. <S> It would be a good addition. <S> The other example is Tic-Tac-Toe. <S> The game is set up so that two humans can play, or a human against one of five different strategies, or the strategies against each other. <S> There is also a 'tournament' display, which shows the results of each strategy playing the others 10,000 times. <S> The five strategies are: Idiot, picks a move at random Naive, tries for center square, then corners, then sides Blocker, chooses a move that prevents the opponent from winning Winner, chooses a move that will win (one superior to that, but I forget the details just now) <S> These strategies are implemented using inheritance, as a hierarchy, so you can explain that. <S> The game board and turn-taking and scoring and so on are implemented using OOP principles, so that fits easily also. <S> There is something here to engage children of varying ages and understanding. <S> Just the idea of "playing against the computer" is interesting. <S> The program is not very complex. <S> I think it could be expanded easily to checkers. <S> Chess would be more ambitious, and probably lose most of your audience anyway. <A> They have a number of great lessons introducing many core programming ideas without needing a computer.
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As a quick introduction to some programming lessons, I highly recommend CS Unplugged .
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Advantages and Disadvantages of Teaching Block-coding Languages Such As MIT's App Inventor? I'm thinking about teaching App Inventor to students who have just begun their adventures in the programming field. MIT's App Inventor is based on block-coding, where the user designs the UI and then designs their functionality with block coding. However, it has so much more potential than traditional drag-and-drop languages as mentioned in an article I found on this website ( Placement of App Inventor in high school CS curriculum ). I think it's a great way to get students started on learning how to program (basics of coding and how to work out solutions), but I'm afraid it also might be a bit dull for those who already have had some experience with other programming languages. What are some advantages and disadvantages of teaching block coding? <Q> Student's Opinion Not a definitive answer by any means, but thought that I might add what I have learnt... <S> I am 16, but first got exposed to block-coding at the age of 9. <S> While I continued with more advanced forms and still make use of them (notably, LEGO Mindstorms), I grew out of block-coding very soon, and progressed to what one may call "real"-er programming languages. <S> That said, I'm the head of the programming/computer club at my school and have noticed that students who were first exposed to scratch <S> (A block-coding language developed by MIT which it taught at junior-middle school at my school) pick up "real" programming languages quickly, since all the basic concepts are already known to them. <S> While teaching my juniors JS or C++ I'll often compare a concept to its equivalent in Scratch. <S> That said, the obvious disadvantage is that scratch is basic , and doesn't cover advanced concepts (return codes, arguments, etc.) <S> However, it is , indeed boring to those who have already had experiences with programming, and this is a problem to which you really should find a solution if you wish to move ahead with GUI-based programming languages in your curriculum. <A> The main attraction of block-based programming languages is that they expose users to the fun aspects of programming (creativity and design) without requiring them to deal with the less fun aspects (such as syntax and obscure errors). <S> This enables students who might have dropped out of an introductory C++ course to get a taste of programming, both to expand their understanding of the world around them (since they use programs every day) and to motivate some of them to learn text-based languages when they hit the limits of block-based languages. <S> Some disadvantages of block-based languages: <S> Some students think that they are not really programming . <S> ( I disagree. ) <S> I encourage you to explicitly address these misconceptions. <S> Don't assume that students who have seen other programming languages will be bored. <S> Creating phone apps is hard, so the ability to do that may be of interest to them. <S> If they are extremely advanced, you can encourage them to contribute to App Inventor, which is open source. <S> Disclaimer: I was part of the App Inventor team and am co-author of a book about App Inventor . <S> I have taught App Inventor at the college-level (to non-majors). <A> Often beginners don't know where to begin when given an assignment. <S> They may stare at a blank screen with a blank look. <S> Once they start typing they may make many errors and become frustrated. <S> Block based languages can help with this as they normally have a UI that shows all of the options that are available at a given moment. <S> The UI itself serves as a prompt for what might be added to that nasty blank screen. <S> It also provides things such as correct spelling and correct nesting of elements as well as (possibly) giving error highlighting and correcting as well as pretty-printing. <S> Block based languages need not be especially limited. <S> I have built and used such systems that create and show a textual version of the program and it can be in a real language or in some subset suitable for beginners. <S> The user can, for example, create Java classes, methods, statements, including structured statements, etc. <S> It is challenging, though not impossible to build such as system that gives complete access to the standard libraries as well as the complete language. <S> Such systems can keep a structured form of the program (e.g. a parse tree) as the internal structure and can therefore produce the output in various formats such as text and structure diagrams. <S> This is relatively easy to do as the user enters structures directly. <S> Additionally, such a tool can be used to storyboard an application, creating the class structure with key methods and then take its output, which can be just text, into a more full featured IDE. <S> One of the problems that novices have with learning programming is that, too often, they are asked to write when they have never read any interesting programs. <S> Reading good programs is a good way to help people understand program structure and good style. <S> But few courses are taught that way. <S> A block-based tool is, in my mind, a sort of intermediate point between the extremes of reading little before writing and reading a lot first, since the available options are visible and it is difficult to make a low-level (lexical or syntactical) mistake. <S> Finally, such systems are normally (though not always) built in such a way that the learner can get near immediate feedback from the execution, with compilation, etc. <S> handled automatically. <S> If the program being written is graphical in nature this can be a big motivator.
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Scratch and MIT App Inventor are very similar, and both are taught to my juniors at school, and students generally appear to enjoy these. They are not as accessible as text-based languages to students with visual and motor disabilities.
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Popular demonstration of cryptographic tools I'm looking for an activity for highschoolers/college-freshmen that will demonstrate crypto topics (e.g., encryption, signatures, zero-knowledge), and will be fun and motivating. It is supposed consist of small tasks that the audience can do by themselves (=no complicated math). I vaguely remember seeing a website with suggestions for such activities, but I cannot find any information now. Any suggestions / ideas? <Q> There are some engaging lessons on encryption in Unit 4 of the AP Computer Science Principles curriculum from Code.org. <S> Lessons 5, 6 & 7 take students from the concept of encryption using a caesar cypher, to a vigenere cypher, and then through the concepts of public key encryption. <S> Students usually have fun with the widgets that interactively demonstrate the caesar cypher ( https://studio.code.org/s/csp4/stage/5/puzzle/2 ) and vigenere cypher ( https://studio.code.org/s/csp4/stage/6/puzzle/2 ). <S> There are lesson plans with student worksheets and videos that support and extend the ideas the students are exposed to when they play with the widgets ( https://curriculum.code.org/csp/unit4/ ). <S> The materials are free to access. <A> I thoroughly recommend Cryptool2 . <S> It's an open-source GUI where you can drag and drop different algorithms, inputs and outputs and see the results in real time. <S> It can be used to show very basic caesar cypers to customizing advanced encryption and hashing techniques. <A> Have you considered a practical example like teaching PGP email encryption? <S> An example lesson based scenario would look like: Explain the basics of <S> PGP and Key based Cryptography - the "Art of the Problem" video linked elsewhere on the answers I agree is the definitive explanation of the Diffie-Hellman Key Exchange theory. <S> This should be sufficient to work practically with encrypting /decrypting with PGP. <S> Students create a set of keys: public key for sharing, private key for keeping. <S> Students share their public keys in a place where everyone can see them and know who's is who's. <S> This is where Keybase would be useful, but you could also just put them all in a public gist or paste bin. <S> It is safe to share a public key. <S> Students can now use the public keys to send messages to each other and publish the encrypted messages in another public place (same pastebin, eg) or via email. <S> Some interesting activities and discussions: <S> How can I decrypt a message meant for me? <S> What happens if I take amessage encrypted for someone else and use my private key to decrypt? <S> What practical use cases could this type of encryption (key exchange)solve? <S> (TLS/SSL probably the easiest reach). <S> What challenges doesthis type of technology create for law enforcement and regulators toprotect against fraud or other nefarious activities (terrorism, moneylaundering, etc). <S> How can this type of activity improve thetransparency and accuracy of information (PGP signatures of codecommits on open source projects, eg). <S> If there are both nefarious andgood uses of this technology, how do you decide if it should belegal, or illegal to use it? <A> When it comes to explaining asymmetric cryptography, I've seen an incredibly simple yet potent analogy used time and time again. <S> This analogy can be found in this Art of the Problem video around 2:40. <S> This simple example could easily be done in the classroom, and can explain the basic principles of asymmetric cryptography without the usual requisite mathematics background.
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Keybase.io has a browser based crypto solution for doing encryption / decryption and while I don't recommend for "real" crypto, it is a great convenience tool for showing how public/private key encryption works without the need to address pgp tools installed on a machine or access to a key server.
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Are programming contests beneficial to students? Background: I’m not entirely a CS educator, but I did run into a debate on whether programming contests are good for students. A lot of people around me have fun in programming contests. Usually, those contests require participants to “solve” several problems (like 7 to 8) within certain time (2 to 3 hours). Students are ranked by their scores, calculated from the number of problems they are capable of solving, and then the time spent. There are test cases on the submission system to which students have to submit their source files, and the submission “passes” when it compiles to a program which passes all the test cases. Given all these, while students are (probably?) good at problem solving skills, there are several problems: Students focus too much on the time spent on writing their programs. Therefore, they employ a lot of poor practices. For example, they always use short variable names, universal headers (#include ), using namespace std; etc in order to speed up their typing. They claim that iostream is implemented on top of C’s stdio and so they use printf even in C++. They always put extra assumptions. For example, while they know how to find the “unpaired” integer in an integer array (by taking the XOR sum), they won’t think of how to check whether the array has only one unpaired item. Also, they usually allocate large arrays in advance and skip bounds checking (they believe the array is large enough), which create concerns in both program stability and security. They don’t understand how to maintain a large project. Since OOP (usually) requires them to type more, they, for example, manipulate raw arrays with a part of custom heapsort algorithm, instead of creating a struct representing a heap, when they are writing in C. While sometimes OOP is unnecessary, for them code reuse is either impossible or requiring a lot of copy-and-paste. <Q> Contests are useful for students who already self-identify as programmers, are motivated by competition, and enjoy the high-stress environment of a competition. <S> But like you said, the skills acquired by participating in programming contests aren't always useful outside of that environment. <S> I'll also note that your examples are all very math-oriented, so the contests might be geared towards students with a more mathematical background. <S> But they're less useful for students who are not motivated by competition. <S> Notably, students from under-represented groups or who don't self-identify as programmers are less likely to participate in these , and requiring them to participate can actually discourage them from pursuing computer science. <S> So, while programming competitions might be one small part of a course, I'd recommend balancing it with other activities that might help other types of students, and pointing out the problems with "competition code" that you mentioned in your question. <S> I'd also recommend focusing on " hackathons " or " game jams " more than competitions. <S> These have the fun and motivation of a competition, but it's more of a collaborative / cooperative environment. <S> This can be beneficial to students regardless of whether they already self-identify as programmers. <A> While I think that all of your observations are correct, there are other considerations. <S> I'm not a big believer in these contests, nor in the kinds of problems that students are asked to solve in them. <S> However, the issue of student enthusiasm for programming (as a part of CS) is also very important. <S> IF you have a bunch of students who need external motivation such contests can, perhaps be helpful. <S> On the other hand, the "take no prisoners" ultra competitive attitude that is exhibited by many young males is a negative consideration. <S> A more cooperative environment would be better preparation for future endeavors in CS, I think. <S> Some competitions, I note, are for teams, not individuals. <S> And competition against your own self is likely a good thing whereas competition against the "other" has a down side. <S> Finally, I worry a bit about preparation for these contests. <S> If your class attends to the issues 1-3 (and others) that you list, you are likely doing a good job. <S> However, if the entire course is spent in working on small, tricky problems (Solving NIM, I call it), then the students aren't really learning what it is to be a "player" in CS. <S> Only a very small fraction of the time spent by a professional or an academic in CS is spent on such "cute" problems. <S> Sometimes that way of thinking can be very helpful, but not very often. <S> Structure, correctness, usability, extendability, etc. are all more important in general. <S> I note that the OOPSLA conference (later SPLASH) of ACM used to have a Design Fest in which teams of folks (adults) would create an OO design of a fairly large system. <S> This sort of thing can be competitive or not, but doesn't involve coding. <S> Later they added Code Fest in which other teams would implement some design from a Design Fest. <A> Time pressure is a given in industry. <S> Schedules are driven by a number of factors - company cashflow, legal requirements, changing business environment - which have non-negotiable time constraints. <S> Even professionally, programmers have to make a snap decision about speed versus robustness, and there are often times that speed is critical <S> and you can come back for robustness. <S> Any student that wrote their own heapsort in the middle of a time constrained project should lose marks unless it can be demonstrated that it required less time to build and gave a better result than the facility built into the language. <S> Unless you have Dijkstra Version 2.0 in your class, I would not expect this to be an issue (but leave the door open for appeal just in case). <S> Good code is time saving code. <S> Using Java as an example (given my handle, you can guess why, but equivalent practices work in almost any programming language), you can design in javadoc and interfaces, then implement the interfaces. <S> This allows you to follow a complete waterfall methodology (ugh!) with documentation, yet still code at turbo speed and produce robust code. <A> Some will love it, a few will excel, most will hate it. <S> Around here we have elective courses preparing for programming contests. <S> They cover more advanced algorithms, more in-depth C++ (or Java, or what have you) and do lots of "hands on" training (e.g. solving problems to be submitted to online judges).
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Programming contests are useful for some students in some contexts, but they're harmful to other students in other contexts.
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How important is it that I know all of the words for the technical terms when mentoring in my second language? Every year for the past few years, I've been mentoring at Scratch Day, helping the kids with their projects during the course of the workshops. The problem? This takes place in my second language, which I don't use Scratch in. Since I don't regularly find myself using Scratch in that language, I don't really remember the words from year to year, and I'll find myself often going "the one under that one", or "the pink section", or of course "thingy". Does this have a negative effect on the students if I'm not using the terms that they'll be using, because I don't know how to translate them exactly? Especially since for some of these kids, it's the first time they're using the platform. The site itself and everything they're doing has the correct terms; it's just me stumbling giving them the wrong names. Is this actively harmful, or just something that it'd be nice for me to work on, but not imperative? <Q> Words matter. <S> The problem is that the kids need to communicate the ideas to one another and to teachers, etc. <S> They also need a way to integrate their Scratch experience into a larger programming set of ideas that they can carry with them. <S> It is good that you are trying to help, but you need to prepare yourself better first. <S> Scratch menus and documentation can help you do this, of course. <S> As you work, keep a few index cards and a pencil so that you can extend the vocabulary as needed. <S> The glossary itself shouldn't require you to leave the Scratch environment for lookup. <S> Paper is actually good for this - more index cards, perhaps. <S> Another trick you can use, perhaps, depending on the age of the kids, is to have them tell you the names of the terms when you stumble. <S> Make a note of their answer (check its accuracy), and work hard not to stumble there again - more index cards. <S> Imperative? <S> Probably yes. <S> Or nearly so. <S> But don't lose your enthusiasm for working with kids. <S> I'm a bit of an advocate for the use of index cards everywhere, by students and instructors. <S> There is a description of the Hipster PDA in the answer to another question here. <A> First of all, kudos to you for teaching Scratch to kids! <S> Vocabulary forms tokens of ideas that we can pass on to one another, and it is no coincidence that much of early childhood is spent with a parent telling a child, "this is a doorknob", and "this is a can opener". <S> These identifiers allow us to summon, link, and morph ideas. <S> We organize our thinking around names. <S> Stephen H. Webb beautifully wrote : Collecting, naming, and organizing things¯anything, from banana labels to dachshund paperweights¯seems to be built into human nature. <S> At least, that’s what the Bible tells us. <S> The first task God gave Adam was the naming of the animals. <S> God “brought them to Adam to see what he would call them” and “the man gave names to all cattle, and to the birds of the air, and to every animal of the field” (Gen. 2:19“20). <S> No matter how you imagine this scene, its meaning seems clear enough. <S> The gift of language is what separates us from other species. <S> We can name them, but they cannot name us. <S> Proper words will help your students enormously when they move on to their next programming language. <S> Without the vocabulary to act as accessors to the ideas that they have understood in your workshop, students will have to independently make connections by linking the underlying ideas. <S> This is cognitively taxing, and only some of them will manage to do this. <S> The others will have to relearn the ideas in the new context from scratch. <S> (No pun intended.) <A> How about flipping it around: People don't learn when you just tell them what to do. <S> So when you are asked a question, answer with a question, for example “What section will you find that in?”, ”show me how you would do that.” <S> (Have them be the cat). <S> As teachers we are told not to be the source of all knowledge, to facilitate. <S> Every time I have a weakness, I ask how can I use this to encourage me to teach better. <A> About remember everything <S> You're teaching people <S> but you're a learner at the same time so; is not a real problem for example you don't remember every technical term about Scracth <S> Why is not important? <S> Software development is not about memorizing is about understanding Its more helpful to write a technical guide with the most common terms <S> If you forget something, for example what is an scenario you can go to your technicala guide and find whats is it <S> If you make you technical guide after you will be feel very comfortable writing for example technical documentation <S> For example if you students go from scratch to Java for example, and if you teached them about reading docs, then they will be very fluent cheking out the Java API <S> At the end is not bad not remember everything, why do you guess every programming language, RDBMS has <S> it's own API to read in case, so take it easy
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Build a quick-look glossary for yourself that translates the terms in your native language into the one the kids are speaking.
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What are the "intangibles" that distinguish one university's CS program from another? Both Carnegie Mellon University (CMU) and Yale are top schools. (I attended both; one as an undergraduate, one as a graduate student, neither as a CS major). Their curricula aren't all that different. Yet CMU's CS program is far more highly regarded than Yale's. (And I'm beginning to think that this view is not about the "program" but something else.) One thing that I did notice, or feel, is that CMU's CS department seemed more "authentic." That is, their CS students really seemed to "bond" with the program. The attitude of Yale's typical CS student seemed to be more like that of "doing a job." Assuming, as I do, that the students are roughly the same caliber, what could be the differences in teaching that give one group of students more enthusiasm or passion than the other? Between two highly regarded schools with not too different CS programs, what are the "intangible" factors of one over the other that would produce two crops of students that are very differently regarded by Silicon Valley? <Q> Fair warning, I am not intimately familiar with the programs, and my answers are based in some stereotypes of the institutions and the CS programs. <S> However, given that my answer is based on student selection, institutional reputation may not be a bad way to think about it. <S> While Yale is, by any measure, a top-tier institution, CMU is (at least by reputation) possibly the top computer science program in the world, and at an institution that is otherwise ranked lower than Yale. <S> I would expect, then, that self-selection among students would play a huge part in this. <S> The sort of student who would aim for CMU for CS would be doing it because the opportunities for CS at CMU particularly appeal to them. <S> By contrast, the sort of student who would aim for a CS degree at Yale would be the sort of student who is aiming at Yale first, and also wants to major in CS. <A> While I know a few CMU faculty (and none at Yale) <S> I don't really know anything about their programs. <S> However, I will speculate that much of the difference is in where the graduates wind up later and what they do. <S> How many earn doctorates? <S> How many go on to become movers and shakers in the computing world. <S> (Some Yale faculty graduated from CMU, actually). <S> But the biggest factor may just be the relative size. <S> CMU has quite a lot larger faculty in CS than Yale. <S> It has six designated faculty specialties, some of which are larger than the entire Yale faculty. <S> The size leads to a lot of synergy, especially as the CMU faculty aren't limited to one specialty area and several contribute to more than one. <S> CMU also has a number of associated institutes, mostly government funded, to do important research. <S> I doubt that the quality of education at Yale at the undergraduate level is much different from that of CMU, however. <S> But the same can be said of many other institutions as well. <A> Here is my standard advice. <S> Spending the price of a house on an undergraduate degree is a stupid mistake. <S> One of two things happens. <S> You lug around a giant slug of debt until you are 50, or your parents are treated to a nine-lives retirement. <S> This advice is inapplicable if you have $300,000 sitting around to burn. <S> If you can get a big scholarship that makes the price unstupid, you can go for it then, too. <S> Be smart. <S> If your state has a quality university system, avail yourself of it. <S> Follow the advice in Joel Spolsky's article ( https://www.joelonsoftware.com/2005/01/02/advice-for-computer-science-college-students/ ). <S> Try to get a co-op or internship and gain some real experience in undergraduate school. <S> When do you get interested in the big-name schools? <S> This is for graduate school if you deem that necessary. <S> If you are a star, someone else will be paying the freight for you to study. <S> In graduate school, you can gain access to the big-name professors in a reasonably small class.
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Moreover, many of the faculty at CMU are world leaders in their fields, though that is also true at Yale.
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Best way to install and maintain windows 10 in a computer lab I’m looking for the best way to maintain a school lab. There are 20 PCs in the lab. All with windows 10.What would be the best way to configure them, so that the student will be able to use them, program in visual studio, eclipse, etc, but will not be able to corrupt the system?Or provide a way to restore some baseline.Currently using toolwiz timefreeze, but experiencing a lot of problems. Edit: while investigating the options and reading the (excellent) answers, I started to wonder, why not use windows built in functionality? Prevent windows destruction: provide the students with a user that cannot do installations and has it's own folder space. Restore: Use windows restore.Am I missing something? Did someone tried it? with this solution, I would not need to install anything... <Q> I have experience managing a lab for student-use. <S> We utilized Deep Freeze . <S> I was not responsible for configuring it, but based on what you say you would like to have in terms of OS management, I believe it would check those boxes. <S> We could set specific times for booting up and shutting down. <S> Additionally, we could restore a non-corrupt image each day if something happened. <S> It allowed extensive control and security. <S> I'd encourage you to look into it. <S> I also don't know the cost, so I can't speak to what you'd be paying per device. <S> However, it worked incredibly well across campus. <A> If I had to do it <S> I would then use Virtual-box's snap-shotting tool to reset MS-Windows every time a student logs off. <S> Price: zero; Cost: probably some training of IT support staff; Time to restore: near zero, the time it takes MS-Windows to boot. <S> though you could take the snapshot after boot, to make it faster. <S> Other benefits you get Debian Gnu/Linux, as used by the top 500 super computers and most of the internet and web. ) <S> Alternatively <S> I would run Debian Gnu/Linux with Mono-Develop and Eclipse. <S> Mono-Develop is a .net IDE. <S> It is very similar to MS's Visual Studio: both are better than each-other, in different ways. <S> It is hard to judge which is best. <S> However Mono-Develop is Free. <S> That is you have Freedom how you use it, you are also free to copy it, and to install it on any computer (including student's computer), and are free to keep it installed after graduation <S> (there are other freedoms also). <A> We are using bwLehrpool for very large installations. <S> The project wiki is here https://www.bwlehrpool.de/doku.php/allgemein/was_ist_bwlehrpool , but unfortunately it is in German and the service is for universities in one of the German federal states, but maybe this answer is helpful for someone in the same situation as we are.
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I would run Debian Gnu/Linux on each machine, and then run Microsoft's Windows in Virtual-box.
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Is it okay to teach C++ to my 7 year old brother? I was thinking this for quite long, should i teach my little brother about programming in the age of 7-8? Because it will help him in the future in 12th standard and in university life. I want him to learn C++, Java, Html. What do you think should i start teaching him or let him grow more till 10 or 12? <Q> I want to tack on to Buffy's answer by focusing on one line from your question: " I want him to learn C++,Java,Html" (emphasis added). <S> The bigger question should be " <S> What does <S> he want to learn?" <S> Part of the beautiful challenge that is teaching is getting students to want to learn what we want to teach them. <S> What has your brother shown interest in? <S> What has he told you that he wants to learn? <S> What are his hobbies? <S> How could something about those hobbies be expressed/constructed in a program? <S> Above all else, where do his interests align with what you can teach him? <S> I'd encourage you to read this thread about starting students in Python, this thread on engagement with computing, this thread about programming languages for teenagers (shout out to Processing!), and <S> our recent HNQ about the age at which students should begin learning programming. <S> Make it fun and engaging for him. <S> Have him build a game, one that he himself would want to play. <S> The language skills will come with time (and intellectual maturity). <S> What you can do now is two-fold: pique his interest for the future and teach him the essential concepts of computational thinking that underpin programming in any language. <A> C++ seems like an awfully steep climb for someone that age with no experience. <S> I'm not sure what educational resources are available directed at that age. <S> I'd suggest that you start out with something more forgiving. <S> Python has been a pretty good choice and has an OO core without quite so many "guns, knives, and clubs" which was an original description of the difference between Java and C++. <S> Most important, however, is that there are materials available for both Python and Java that are directed at younger learners. <S> In Java, for instance, the Greenfoot system provides a graphical system that provides both a visual environment and a fairly strong programming support environment that is amenable to younger learners. <S> I don't know of anything quite comparable in Python, but there may be some things. <S> One of the things that you might want to think about is that a new learner doesn't need to start with a bare screen and no support, building everything as they go. <S> Virtual worlds can be constructed, by teachers or authors, that enable a beginner to do interesting things much earlier than they can if they just start by learning int variables and if statements. <S> If you spend all of your time learning syntax and low level ideas you may not get to do anything interesting and so get bored easily. <S> Better in many ways to work in and modify an existing system (in well considered ways) than to have to build up from nothing. <A> I have tried to learn and teach C++ , I have seen others try to learn or teach it. <S> I have seen people come out of university, having “Learnt it”. <S> I have seen no success. <S> None of these people have learnt it well, few have learnt it at all. <S> The only exception are those that first learn another OO language. <S> The best OO language to learn first is Eiffel. <S> However I would not start with OO (For anyone). <S> For a 7 year old, I would start with Scratch. <S> Consider also, not using a computer at all until age 11. <S> That is no computer at all: no desktop, no laptop, no tablet. <S> There is much computer science that can be learnt without a computer. <S> See CS-unplugged. <A> It's okay, but I think it's a bad idea. <S> They liked it, but I thought it was a waste of time because the language, toolsets and many of study materials are not kids friendly. <S> Almost everything about C++ slows them down compared to higher-level languages such as Python and JavaScript. <S> The better order for kids to learn programming is Scratch -> <S> Python -> JavaScript. <S> Once they build a solid foundation how to program and solve problems with Python and/or JavaScript (this will take at least a year or two), you may consider teaching more advanced languages such as Java and/or C++. <S> Unlike olden days when there were good reasons to learn Java or C++ as a language of choice, the benefit of learning Java or C++ is shrinking fast for beginners these days because there are so many materials and opportunities available for easier languages and growing support for those languages. <S> For example, many programming competition websites and event the UASCO training site support Python. <S> In the past, many of sites only supported Java and C++.
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I've taught my kids C++ when they were age of 9 using a beginner book on building a game using C++ after they had a brief education on Scratch and Python.
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Should one study programming by doing hard problem? As one learns programming, how useful it is to spend time to solve hard problems? Like, I saw a problem solving site where one task is for example to find a regular expression for decimal numbers divisible by 9 or do regular expression for a particular problem that is as small as possible (in sense of number of characters in the expression). Is there worth of spending time to try those kind of problems or should one always try to solve problems as easily as possible? <Q> It is probably a mistake to always do one or the other. <S> If you are learning a hard task (becoming a competent programmer), it isn't helpful if you mix in another hard task as well (hard problems). <S> Initially, it is good to write programs for problems that you already understand well, so that you can focus on the creation. <S> A program has both form and content. <S> If you work on very hard problems exclusively, it is possible that you will wind up just hacking a solution together without any elegance. <S> But if you never solve hard problems it won't become clear to you why advanced programming structures and paradigms are needed. <S> But mix in a harder problem or two as you go. <S> Then when you become more proficient with the forms, move to harder problems and occasional very hard ones. <S> You are stretching your brain in two dimensions here. <S> Eventually you want it to be very flexible. <S> But you can stretch more in one dimension than the other at a time. <S> If your problems are so difficult that you get frustrated <S> then you may not make much progress on any dimension. <S> And, of course, problems that seem hard to a novice programmer, may not seem very hard to a pro. <S> You learn a lot of tricks-of-the-trade as you go along. <S> Also the problem that you mentioned doesn't result in a very big program. <S> It is a bit tricky, of course, but very small as programs go. <S> You want to reach a place where you can intelligently create very large programs. <A> This question reminds me of the thought-provoking question: Would you rather slay one horse-sized duck or 100 duck-sized horses. <S> For beginners, I recommend solving lots of simple problems. <S> This practice is crucial to learning, because all the programming concepts are new, and you need to experience them. <S> For example, sometimes it takes several programs that use a single for loop to really understand <S> how a for loop works. <S> For advanced programmers, the hard problems can be beneficial. <S> But what makes them hard? <S> Is it the length of the program? <S> Is it low-level or advanced concepts (e.g., threads). <S> I would accept a very difficult assignment if it meant learning something useful or desirable. <S> In general, I tell my students to practice writing lots of programs, no matter how small/large, easy/difficult. <S> Any program is better than not writing one. <A> Is there worth of spending time to try those kind of problems or should one always try to solve problems as easily as possible? <S> You should work on problems that are fun and interesting to you, and that are slightly harder than the problems you're already comfortable with. <S> Programming is a craft , similar to playing a musical instrument or playing a sport. <S> You have to practice <S> programming to improve, exactly the way you have to practice playing the piano or throwing a baseball. <S> When learning to play the piano, do you always play the songs that are easiest for you, or do you always try to play the hardest song ever written? <S> When learning how to hit a baseball, do you only practice with slow underhand tosses, or do you only practice with 100 MPH curveballs? <S> The answer is none of the above. <S> You practice by getting a little bit better every day. <S> For piano, maybe you learn a new song that's a little bit more complicated than the song you learned last month. <S> For baseball, maybe you practice with somebody who throws the ball a little bit faster over time. <S> The same is true of programming. <S> You have to meet yourself where you are. <S> Don't spend too much time on stuff you already have memorized (although, there is some merit to programming kata ), but don't spend too much time struggling on impossible problems either. <S> In other words, you should try to keep yourself just slightly outside of your own comfort zone. <S> You also might want to read about the zone of proximal development . <S> Specifically, here's what I recommend <S> : Give yourself an achievable goal. <S> The goal should be fun and interesting to you, and it should be achievable in a reasonable amount of time. <S> A single weekend is a good starting point. <S> Finish that goal, and then iterate. <S> Explore topics that you're interested in, but do it with short achievable steps.
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My advice would be to start out your programming education with fairly easy problems - that you can get your mind around easily.
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Should programming assignments be graded based on results from unit tests or based on the similarity to the correct implementation? Imagine students in a course on algorithms & data structures, which are given homework assignments to implement things like trees, hash sets, sorting algorithms, etc. Due to the high number of students per semester and limited resources, grading is heavily assisted by automatic unit tests. The TAs will still scan through the code, but if all or most of the test cases fail and there is no simple fix in sight, students will get 0 points on an assignment. Unfortunately, this can happen very quickly. Consider implementing a balanced tree as an example. If students fail to correctly reference the nodes, insertion, removal and searching, - despite being implemented correctly if seen individually - will not work and can hardly be tested. As expected, some students do complain about their poor grade and argue that "although they acknowledge that their data structure does not work entirely, they at least implemented various sub-tasks correctly" . This may even be correct, but the TAs very often do not have the time to dig deep in the code and grade the internal functions of the students implementation. Especially for more complex data structures, it would also take too much time to fully comprehend and even debug the (erroneous) implementations. My question is, if it is okay to grade programming assignments based on this external view (does the implementation pass the tests?) or should grading rather be based on an internal view (are the things implemented by the student correct if seen individually?). One important remark: In this specific scenario, students were not given the unit tests, since they are expected to test their implementation themselves. <Q> Actually, life isn't so simple as to choose one or the other here. <S> Code needs <S> to be well structured and it needs to be correct. <S> Given that students are learning, you can't really expect that they will be perfect on either of these <S> and so you need to take both in to account. <S> A program could, be well designed and built but have some, as yet undiscovered, flaw that prevents it from passing its tests. <S> If the students hack it up to get tests to pass they are going backwards, not forwards. <S> CS students have a lot to learn. <S> Programming is important, but not the most important thing. <S> But to advance on many of the other goals of the CS curriculum, students need to build good code. <S> Even better, would be the ability to build maintainable code, since many of them will start their careers in programming-heavy jobs. <S> Even if they go to grad school, much of what they do will depend on being able to write good code. <S> So, in grading, points should be gained or lost depending on both code and correctness. <S> It could be something simple or profound. <S> In my view if a program can't be understood easily and/or seems to be hacked together, it should receive few points. <S> If a program, on the other hand, passes few tests then it is a much more subtle problem that needs deeper analysis. <S> Don't neglect it. <S> In the question heading you talk about the "correct implementation". <S> I worry about that. <S> Students should not be graded on similarity to any reference implementation, certainly. <S> There are more than a few ways to write a correct program. <A> I agree with Buffy, the question would be perfect for cseducators SE. <S> But still, I try to give an answer which might be generalized to other disciplines as well: <S> Of course, this is absolutely ok - but it affects your teaching style and goal. <S> If you want the students to be 100% perfect, this is the way to go. <S> It's a hard lesson, but in real world scenarios they are facing more or less the same situation. <S> My Physcis teacher at school took the same attempt and argued, that it does not make a difference if you want to drive to school and crash into the tree next to school or next to your house - you don't make it! <S> I fully understand the burden of reading students code - I do the same and it can be a great pain. <S> But if you do it, you can give individual feedback and you'll understand, which are the most common mistatkes and adress them in your course. <S> One compromise could be to offer different test sets, let's say some tests for each function needed for the complete task. <S> That would allow to give points partially, but still you can not give points for a correct recursion, loop or whatever. <S> An additional thought: You might consider giving a few test cases so the students can at least test if their code understands the input and delivers the output in a format your test understands. <S> I don't know if this is a real world problem with your students, but it would be an issue with mine <S> ;-). <A> The 'external view' is important as it ensures the submission is correct. <S> These tests should be similar to Acceptance Testing since you are checking whether the submission meets the 'business' requirements i.e. the requirements laid out in your question. <S> I highly recommend automating this process with unit tests or console based tests (check output matches the expected output). <S> The 'internal view' is what motivates your students to do better since only a person can judge this properly. <S> Students are not motivated to write good code when they are only being judged by automated tests. <S> I recommend looking over each student's submission and ensuring that they have followed the correct approach have met proper code quality standards. <S> Of course, you can't give a lot of time to looking over each submission UNLESS the 'external view' tests are automated and you don't have to download and run the code for the 'internal view' reviews. <S> I suggest automating your process using AutoGradr <S> (disclaimer: <S> I am the author of this free tool)
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If the code is not correct, then someone needs to make an analysis about why the code is failing.
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Code highlight for classroom use I am thinking about "dissecting" my code with students, going line by line and commenting (why is this the condition of the while? What does this piece of code do?) A simple example can be found here: https://docs.google.com/document/d/1mxTE_E2_YKq-yhaXAfBxYP11uaRm7bSXTnP55bMnPyQ/edit However, I would like a better tool for the job. As you can see, in docs, the comments are far away from the code and not linked to their respective by any visual cue. They are also all on the same color. I tryed some highlighting tools for docs, but they seem to just highlight,not add colored comments I am looking for ideas, inside or outside google docs, to do the job. For inspiration (no way am I ever doing something this pretty!) here is an image from a headfirst book <Q> I would suggest two things. <S> Both of them, however, require that you give them printouts of the code so that they can make notations of their own without having to use any tool. <S> Also, I'm assuming that your code is in small pieces, say, short methods. <S> For me, a method is long at about five lines and a method that covers a page is incomprehensible. <S> I have anecdotal evidence from industry that the latter is also true. <S> Ask the students about it and talk about it. <S> Asking is probably more effective. <S> You don't need to write anything. <S> Another uses a tool like Powerpoint. <S> You can flip between pages as you talk, flipping both forward and backward as needed. <S> But, again, ask the students to explain, rather than giving your own explanations. <S> This way you can pick up misconceptions they might have and correct them. <S> Make sure that the code itself has the same alignment on each page. <S> Then when you flip, only the highlighting changes and students don't need to readjust the context. <S> Perhaps you can project against a writable surface rather than a screen. <S> If you project on a whiteboard (and can ignore the glare) you can use marker pens to annotate - especially when the students say the right thing. <S> Make it interactive. <S> Broadcast is much less effective. <S> Also, since you are putting effort in anyway, make sure that you always use intention revealing names in your demo code. <S> Don't use <S> x, y, z, i, j, <S> k. Make the names come from the problem being solved, not the solution. <S> For example counter is a name from the solution. <S> But negative_value_counter is a name from the problem (of counting negative values - duh). <S> In this way, if you are primarily teaching them about how to structure programs, you can focus on the structure (if, while, ...) <S> rather than having them wonder about the purpose of abstract names. <A> I'm taking a very basic approach when I do it: I use my Editor and comment line by line. <S> This way I can directly show alternatives and effects if something does not work as planned. <S> Usually I'm developing the code live to avoid that students get distracted by the code to come. <S> The good thing about this approach is, you can show them how you can develop a program from scratch and how you are digging into the finer aspects of problem solving. <S> E.g. you can "forget" one condition in a loop and create an endless loop - and show them how you can find the mistake. <S> Another thing I did which comes closer to your UML example: I'm using a surface tablet in my class and sometimes I'm just taking a quick screenshot and use the pen to write on this screenshot. <S> This works nicely and does not need additional tools (once you are having a tablet with pen). <A> You need to know about http://pythontutor.com/ - they have line-by-line execution and a diagram showing memory and how it changes. <S> They also have more than just Python, they have Java, C, C++, JavaScript, & Ruby <S> I have used this resource in my classes and it makes it so amazing to explain how memory, references, and classes work. <S> The C tutor really helps with pointers as well. <A> I create code-comprehension sheets outlined in one of two ways (depending on the code) <S> : code on the left, with questions on the right, or code with questions interspersed like comments. <S> There are a few uses for such sheets: <S> Check comprehension of what we've just gone over. <S> Force students to try to examine and digest code <S> prior to going over it together (to increase interest/retention when we go over the material.) <S> Assessments. <S> Typically I will do this with 1-3 pages of code that has to be understood on several different levels in order to make sense of it. <S> Think objects, or assembly code.
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Just write on the paper. One method, assuming that you have given students the code is to just project it from your normal IDE and highlight it with the mouse. Build a deck in which each page shows exactly the same code but with different sections highlighted as you desire, using one or more colors.
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Do you know of a complete textbook for teaching databases? The textbooks that I know about, teaching databases, are not complete. In the sense that they lack a complete set of assignments, homework, projects, slides and instructor manual. Do you know of any new textbook that is complete in this sense? <Q> I've taught a lot of people SQL in person (over 3000), and I've had to cobble together materials out of a bunch of resources to do it. <S> For Exercises: <S> http://sqlzoo.net http://pgexercises.com <S> https://www.codewars.com/?language=sql <S> For slides, you can use mine, just fork them and remove the branding (they are CC-licensed, the branding is just there to look nice): <S> https://slides.com/lizh/sql-intro <S> Make diagrams or have students make diagrams with: https://app.quickdatabasediagrams.com/#/ <S> Usually <S> the way I see SQL courses go: <S> Start by covering enough to get them through querying- <S> have them start with one of the exercise sets above. <S> You may want to break it down into a few class periods - basic querying and filters, followed by joins, and then more complex joins / functions. <S> Next, have them model data. <S> If you model some data for them, then present a problem for them to do in groups, they usually get the idea pretty well and can self-grade. <S> Then, have them choose something to model individually. <S> Students should first try to model some data that has 2-3 relations, then model data with a many-to-one relation, then more complex relationship models (relating through 3 or 4 tables). <S> Some really great things to model, either as a class or as individual projects: Books <S> (books are great because you can start with a simple model, then factor it out to third normal form, and then identify where it would vary by application greatly, eg amazon.com vs a library, they need different data models). <S> Keyboard shortcuts (because you can relate them to applications, and keys) <S> Transit (routes and schedules and busses, most students are familiar) <S> Food (you can go a million different ways with this, this is a very difficult data model to do properly) Content (users, posts, comments, upvotes, block list. <S> Do this one yourself as an example, it's in too many walkthroughs to be a good assignment.) <S> If this helps, I am the CTO over at enki.com, and we have an open-source CC-licensed curriculum here: <S> https://github.com/enkidevs/curriculum and a free app students can use to do daily practice with SQL here: https://enki.com/ <A> All too often the focus is on Microsoft products. <S> In this case, Access is the database used in Shelly Cashman Series® Microsoft® Office 365 & Access 2016: Comprehensive, 1st Edition , (2017). <S> Table of Contents: <S> Microsoft's New Productivity Tools for School and Work. <S> Office 2016 and Windows 10: Essential Concepts and Skills. <S> 1. <S> Databases and Database Objects: An Introduction. <S> 2. <S> Querying a Database. <S> 3. <S> Maintaining a Database. <S> 4. <S> Creating Reports and Forms. <S> 5. <S> Multiple-Table Forms. <S> 6. <S> Advanced Report Techniques. <S> 7. <S> Advanced Form Techniques. <S> 8. <S> Macros, Navigation Forms, and Data Macros. <S> 9. <S> Administering a Database System. <S> 10. <S> Using SQL. <S> 11. <S> Database Design. <S> Index. <S> Also worth a look is Concepts Of Database Management 9th Table of Contents: <S> Introduction to Database Management. <S> The Relational Model 1: Introduction, QBE, and Relational Algebra. <S> The Relational Model 2: SQL. <S> The Relational Model 3: Advanced Topics. <S> Database Design 2: Design Method. <S> DBMS Functions. <S> Database Administration. <S> Database Management Approaches. <S> Appendix A: <S> Comprehensive Design Example: Marvel College. <S> Appendix B: SQL Reference. <S> Appendix C: MySQL. <S> Appendix D: "How Do I" Reference. <S> Appendix E: <S> Using Access to Create a Web App. <S> Appendix F: <S> A Systems Analysis Approach to Information-Level Requirements. <S> Both books are from Cengage, which does very well with print and ebook options, including a student access area to download materials for the practice work of each chapter and source material for the exercises. <S> They also have extensive material available online for instructors, often including PowerPoint slides and test generators. <S> (As a student, I've found the Cengage books I've used to be good for learning from. <S> The download area sometimes includes even more exercises than the book presents. <S> Sometimes the Shelly Cashman Series® of books seems too elementary for my tastes, but my fellow students have always seemed to like them well enough. <S> So I can recommend Cengage as a resource from a student perspective as well.) <A> Database Systems Concepts by Silberschatz, Korth and Sudarshan comes with a comprehensive instructor/student resources web site provided by the authors. <S> You can find slides, assignments and even a web based tool to practice SQL at https://www.db-book.com/db7/index.html <S> If you are an instructor in a qualified educational institution, you can contact the book publisher. <S> They provide additional resources for instructors like solutions to selected end of chapter exercises etc. <A> "Fundamentals of Database Systems" (Elmasri, Navathe) is a good textbook. <S> Still, from the practical point of view, there are no practical assignments one can use for students. <S> Also, there is no complete set of exercises with solutions. <S> Links given above are interesting, but not complete, especially for the normalization process.
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Database Design 1: Normalization. I have found the Shelly Cashman Series® of books to be effective.
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Is learning C++ recommended for beginners? I have heard a lot of people saying C++ is a hard language to learn and is not a good language to start. I myself am a beginner in programming and have jumped straight into C++ as soon as I heard that being a programmer is way more useful for creating games compared to someone who just knows how a game engine works(Its what I heard). So far, I enjoy learning it and have not found it difficult to understand. But I have also heard that it gets harder as you progress. The reason why I decided to learn C++ in the first place is so that in the future when I turn 18, I'll be one of the top choices for big companies and be able to be more experienced than my fellow programmers in the future since C++ is the main language used by big industries. Should I stop now and learn a different language like C or C#? <Q> I wouldn't fuss too much over whether a language is "hard" or "easy". <S> There are plenty of reasons to learn a language. <S> Learning for a career is a great reason! <S> Languages are usually organized around certain central ideas. <S> Haskell is a pure functional language, Eiffel is a pure Object Oriented language, and C is designed to reflect very closely what a processor does. <S> C++ is designed to be a cross between C and object oriented programming, so there are several different paradigms at work at the same time. <S> That can make it a little more difficult to learn because there are simply more concepts at play. <S> However, the early basics should be fairly easy in any language. <S> C++ does appear to be the most heavily used language in the gaming industry. <S> However, there are a few caveats: What sort of games would you like to be involved with making? <S> Browser games rarely use C++. <S> Languages change, but concepts are long-lasting. <S> While learning, keep pushing yourself to learn new ideas, not just new procedures. <S> That way, you'll be better positioned to switch over to a different language if it turns out that the wonderful gaming job you land is actually in HTML5, or Python, or in some language that hasn't even been invented yet. <A> welcome to our community ;) <S> Is learning C++ recommended for beginners? <S> I am thinking specifically of Python in this regard. <S> You can even learn many of the "classic" game concepts and code games using PyGame or arcade- two libraries that provide a lot of support for game development. <S> Reading further into the details below the initial question posed- in your particular case, given that you are grasping it at the moment and not experiencing any difficulty as yet- <S> Keep going and when you have difficulties, do some research, watch YouTube videos, take some of the brilliant MOOCs that are out there, code for fun and pleasure, to achieve a goal, and keep going. <S> It sounds like you are highly motivated, and that is one of the MOST important things! <S> In summary- in general, no- <S> Python (imho). <S> In your case- <S> Yes! <A> Yes some people recommend it. <S> These are the “What is use in industry?” people. <S> However this is the wrong question, it may be easier and quicker to learn several languages first. <S> My experience <S> I have tried to hire C++ programmers. <S> It is very hard, there is a lot of variance between claims and reality. <S> Most people claiming many years of C++ can not write good program (bug-free, easy to maintain …), and graduates have no clue. <S> I could never again try to hire C++ programmers. <S> It is better to hire good programmers, that know another OO language, and cross train. <S> Eiffel is a good OO language to learn OO well. <S> Java, C#, javascript are other popular languages, that while not as bad as C++, are far from ideal teaching/learning languages.
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In general, I would suggest that it is not the optimal choice for a beginner, since there are other languages out there that are powerful, widely supported, used in a range of industries and (perhaps most importantly for a beginner) have a simple syntax with powerful features. I would say Go For It!
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Do some websites block school building/classroom IP networks because they mistake us for possible DDOS? So I had my students go to NodeJS.org to download Node.js, and they did it with no problems. Two days later, I had them go to NodeJS.org again, but none of us could access the site, not even from the designated "teacher's computer" of the classroom I was using. However my laptop, which was connected to the school's wireless service for teachers, could still access the site. I'm assuming classroom computers and the school wireless are on separate networks. Could this mean that the anti- DDos system at NodeJS.org basically mistook us for a potential DDoS and blocked us? There were about 20 students. A week later we could access the site again. So I'm just wondering if anyone else experienced anything like this? <Q> Yes. <S> I have a web development class. <S> If more than 5 people connect to the free hosting site, it stops anyone else from connecting via FTP, since we appear to all have the same IP address. <S> Multiple connections from the same site can be a script running, and most users will not appear to have multiple connections. <S> I do: <S> Demo using the FTP client, go through some of the issues with connecting (error messages etc.) <S> and then, because of this restriction, I will either: 1) <S> Manage the class in groups <S> (if a small class) or 2) Give them a task (ftp their site) to perform at home for review at the next class <S> It is annoying, but as indicated above, it is likely to detect DOS or other malevolent connections. <A> I've had it go the other way... <S> Website (self hosted Moodle) worked while we set it up. <S> Worked fine first period. <S> Same as you <S> I could still get to it from my computer, but students couldn't. <A> It is very common for institutions to use a single IP address and Network Address Translation (NAT) to avoid the problems of getting and maintaining a larger IP address space. <S> As a result a website experiences all of the traffic from the institution as a single user. <S> Depending on the threshold for password failures or rate limiting the traffic may see the school's traffic as a DOS attack. <S> You may be able to contact the provider and see if they can adjust the threshold for your site's IP address <S> - I know this is possible on Drupal based sites. <S> If they are unwilling it might be worth asking if they would prefer that you use, and could recommend, an alternative site that is able to handle schools (and kids who don't type well and who forget passwords).
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Something got triggered on the school network and decided that too many students were going to the site so it got blocked.
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Is the algorithm-recipe analogy a good or a bad one? I am growing suspects that the ubiquitous analogy between algorithms and recipes be not so well founded, especially for theoretically oriented students. I am wondering if this may contribute to the evidence of students having difficulties with even simple loops. I believe that bad analogies make more harm than no analogies, so I ask. My wondering is that recipes, if superficially similar to the idea of sequential steps, do not really encode the logic that is sought to be explained: the logic of state transitions.Of course there are state transitions in recipes, but i do not feel they being the characterising properties , nor are they the target of attention (I also like cooking). State transitions in recipes (and similar physical operations analogies) seem to be not even caused by the "program" but just happening because of physics. And typically what we get from students struggles is exactly their inability to follow (or design) state transitions. Probably because a fundamental property of a real computer program is that of being the acting cause and not the observer of state transitions, and this is not captured by the analogy. Another issue is that computing systems are typically discrete while physical analogies tend to be continuous, both in time and measured (variables) dimensions. What screams for attention in recipes are instead "data" dependency constraints (cannot throw in the spaghetti before the water boils), or a kind of "event-driven" situation, and i do not recall seeing students struggling with data dependencies, which might be because 1. the recipe analogy is good in teaching them or (I suspect more probably) 2. it's not what they need help for: data dependencies being more innate than state transitions, especially in a forcefully sequential environment (of course this is a hypothesis, any experiments known?). On a more concrete side it seems to me that the real world software counterpart of recipes are those things that we usually call scripts: something I love and had made a lot of and which I know perfectly fit their niche problems, but not something that is known for exposing nice theoretical properties, which, I suspect, is what matters more when learning, in order to build a clear mental model of algorithms (and because my pupils are generic science students and not specialist computer developers). Realistic programs, and especially subprograms if we want to divide et impera, are not sequences of operations but sequences of state transitions. What do you think of this analysis? Have any empirical data? Does an analogy that takes more care of state transitions exist and I have missed it? <Q> Actually, you are loading a metaphor/analogy with too much import and influence. <S> An analogy isn't supposed to be exactly the same thing as the thing of which it is an analogy. <S> It is only supposed to be similar to that thing in some way . <S> But not in all ways. <S> To use it well, you need to do a couple of things, one of which is to move away from it as soon as is possible. <S> But the more important thing is to be aware of how the analogy fails to be <S> the thing analogized and to watch for misconceptions in the student's mind that are actually induced by the analogy itself. <S> You then need to give a correcting lesson. <S> I can analogize loops with cooking recipes as: stir the sauce until it thickens. <S> This isn't an algorithm, of course, since it has undefined terms, especially in the stopping condition. <S> If that gives the students a quick mental picture of repetition then fine. <S> But if they put too much weight on "stir" or think that an imprecise stopping condition is normal in programming, then I need to make a correction. <S> Sometimes that correction is with another, better analogy, but usually it is just a more precise and technical discussion. <S> Don't put so much weight on any given metaphor. <S> Use it to introduce concepts but know when it fails and make corrections for those (hopefully few) students who draw the wrong conclusion. <S> You can thus avoid being overly detailed and pedantic, losing students in the interactions between all of the small bits that go into anything complex. <S> I've been told that professional bakers follow their recipes more faithfully than professional chefs do. <S> More careful measuring, for example. <S> But even bakers have to deviate as the flour they use can vary in moisture content, requiring adjustments. <A> I have never been a professional educator for computer programming at the very beginner level, but I have used the "recipe" analogy in a lot of situations where I am not acting as a formal educator. <S> However, I flavor (see what I did there) <S> the analogy, by describing the computer as the absolutely most simple-minded assistant cook that you can possibly imagine. <S> So if you want a cup of sliced carrots, you have to tell them how to slice a carrot, how to know when they have sliced enough, and tell them to keep slicing carrots till they have enough. <A> Firstly, a program is a text and so is a recipe: they are both texts. <S> A text can be read, shared, and edited. <S> The recipe is typically meant to be followed & executed by a human whereas the program is meant to be followed & executed by computer language. <S> Both are meant to be read and updated, refined, adjusted, maintained by humans. <S> Further, a text can be analyzed, for, as you point out, state transitions, and perhaps steps or operations that accomplish those transitions. <S> The recipe starts with raw ingredients and forms them into finished product, whereas the program consumes input and turns that into desired output. <S> Both share the concept of intermediate results that are in turn used to produce the results for the next step and finally the finished product. <S> For another, a text can be analyzed for logical errors, which applies to both recipes and programs: a recipe might have typos; a recipe may suggest doing something in an order that is physically impossible — computer programming has these errors as well. <S> If you post your recipe online you might get feedback on how well it works and <S> what can be adjusted. <S> A code review is similar, though in programming we also have the automated feedback from the compiler or interpreter. <S> Recipes and programs can both be tested. <S> The both allow some variation of inputs and outputs, as well as introducing a notion of acceptable inputs and acceptable outputs. <S> Sometimes these things go unstated, other times, formally stated (a souffle should stand and not fall, a program should produce certain results). <S> As @Buffy is saying you can take the analogy further in that recipes can have conditional steps as well as repetitive sections. <S> Recipes can even have formulas ( <S> e.g. for every 1000 feet in altitude, boil another 3 min).
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I think the analogy holds up rather well. Analogies and metaphors in teaching computing are intended only to overcome the initial static inertia caused when a student has no idea whatever about a concept.
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Thoughts on language for Intro to Data Science? Next term, I'm going to teach an introductory Data Science class for the first time. In the past, others have taught it in either R or Python. My first inclination was to teach it in R because the language is specifically for statistics (and not a general programming language like Python). However, I see a lot of promise in Python's Pandas library. I haven't used Pandas myself, but I have more than enough time that I could familiarize myself with it. What are your thoughts on R vs Python vs a bit of both? Ultimately, the Data Science curriculum exposes students to both. Which do you think is more appropriate to begin? Course details: Prereqs include CS1 (C++) and Statistics Topics include the analytics life cycle, data integration andmodeling, relational databases and SQL, text processing and sentimentanalysis, and data visualization. Emphasis is placed on reproducibleresearch, code sharing, version control, and communicating results toa non-technical audience. First of two DS classes as part of a DS certificate (Minor is <Certificate is < Major) with predominantly Comp Sci and Stats majorsenrolled I am currently teaching the Advanced DS class (the follow-up course)with a concentration on R, but that could potentially change in thefuture as well. Sooner or later, if they complete the certificate, they will get experience in both R and Python. The question is which comes first. I can choose the textbook, but will give strong preference to free,online resources <Q> The biggest strength of R when it comes to Data Analysis is in its data visualization . <S> As you've mentioned it is a more or less dedicated tool for statistical analysis . <S> The thing with Python is that you can easily go a bit off course with the lectures because for Statistical Analysis you'll have to understand, install and work with different libraries/APIs for plotting (matplotlib/pandas/plotly) and processing your data (scipy/pandas again/numpy). <S> These may take different approaches for installing and working with besides being tools on their own. <S> RStudio already sets up everything for you for the most part so you can just focus on implementation; if you happen to need something extra installing packages from CRAN is incredibly easy letting you do it from the script itself rather than opening a terminal with conda or pip or whatever. <S> My notes <S> It will let you focus more on concepts which are general. <S> If you're interested in teaching General Programming as a tool for Data Science and maybe other things, go with Python. <S> If you like both ideas, I'd start with R and replicate results with Python later to show its integration with different tools. <S> This way your students will see both approaches are feasible in the case they go out there and see it in the job market. <A> In my experience, there is less 'overhead' with R, especially if you use incredible resources like Intro to Data Science <S> < https://rafalab.github.io/dsbook/ <S> > <S> and R for Data Science <S> < https://r4ds.had.co.nz/ <S> > You can more quickly focus on data wrangling, visualization and stats. <S> I think R is more bang for the buck in terms of getting at data and meaning. <S> Rstudio/ the R community is very supportive, resourceful and smart. <S> In my first Intro to DS class I had thought I would focus on Python but as I experimented I found that I did indeed need to spend much more time teaching syntax and that took away from the focus on the work. <S> For my new students- coming in to work with data but not coming from a programming background- <S> they really like R. <S> The tidyverse has been a godsend (ggplot, dplyr and other libraries) and the libraries/resources for spatial data are awesome. <S> There is no wrong decision- <S> but I think in future I will stick to R for Intro. <S> Eventually, if professional, one needs more than one language <S> but you'll never get to be a professional if you don't get a start! <A> Python is more widely used in industry and is a general programming language, so will be more advantageous for students. <S> R will be useful if your students aim primarily for life sciences and/or academic jobs. <S> But even there Python is used extensively.
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: If your interest is teaching more Data Science, as a tool in itself , go with R. For my 'natural born programmer' students, they like Python.
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How do I deal with students being unkind to each other when I'm not there? The faculty and students at my small minority-serving institution think of our environment as being supportive and cooperative. This is very important in CS, since programming is a team sport, and students are expected to seek help from each other (and TAs and me). I have heard recently from two unconnected students about other students ignoring or being rude to them (such as walking away mid-question). The complainants don't give names, and I have no idea who they're talking about. Almost all of the students in our program belong to at least one demographic underrepresented in CS and/or in the US. The students who have been mistreated belong to multiple such demographics and think that may be a factor. I have no way of knowing if they're right. Each is the only student of their cohort in their demographic. What can I do to encourage students to better treat classmates? Some have been at the institution much longer than others. The ones who feel mistreated are newer arrivals. While my top goal would be changing students' behavior, we all know it isn't always possible to get people to change. If I can't get people to change, how can I know who should deserve bad citizenship grades or to not get letters of recommendation? I am not interested in furthering the careers of people who mistreat others. <Q> I have a couple thoughts of how I'd handle it: <S> Address it with the bad actors 1-on-1, but don't assume bad faith . <S> We might not know the whole story and there might have been a good reason to walk away from a situation or <S> it is possible that the bad actor has poor social skills. <S> Give them the benefit of the doubt, but explain why that kind of behavior creates a hostile environment that is not good for education. <S> Discuss in class what makes for a good working/learning environment . <S> Not necessarily directly mentioning the situation, you can still emphasize a need for students to take agency in being part of a nurturing environment. <S> I haven't had the exact same circumstances, but I have found it helpful by acknowledging that most jobs require interpersonal skills and that I've known even talented developers who have been passed up for good jobs because no one wanted to put up with their attitudes. <S> In that same notion, I tell my software engineering students that I expect them to behave like professionals and like the class is a part-time job. <S> That includes treating others with respect, even if they don't consider each other friends. <A> This guy's teaching is the best I've ever found on conflict-reducing communication: https://www.amazon.co.uk/Life-Enriching-Education-Communication-Performance-Relationships/dp/1892005050 <S> In summary, keep observations separate from judgments and communicate on the level of needs. <S> Also, empathize first, before expressing yourself. <A> First, as Kevin Buffardi pointed out, don't assume bad faith. <S> Poor social skills may be playing a role, and it's also the case that everyone finds people who just rub them the wrong way from time to time. <S> No one is universally liked. <S> Unless you have a strong reason to believe that there is specific vindictiveness or some sort of "-ism" at the heart of the trouble, you would not be justified in direct penalties (such as poor grades). <S> It is also the case that some people have chips on their shoulder from their own experiences or disadvantages, and this may manifest as inappropriate reactions to others. <S> Additionally, since the students on the receiving end of this behavior won't name names, there is no ethical way for you to discover who the offenders are. <S> You can remind students that the world is small, that the community you are in together is tiny, and that everyone should be pulling for the same team. <S> Everyone is there with goals, everyone there is human (with all of the faults and flaws that that entails), and everyone needs the space and safety to try new things, grow, and learn. <S> That is what you expect from them, and that is what everyone needs in order to learn and feel safe. <S> Finally, reiterate that you are always available to anyone if they would like to speak privately.
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You can mention that there have been reports of some bad behavior, and you are trying for the moment not to punish, but to appeal to their deeper senses of self: they are simply capable of being better people than that. If you find it is a continuing problem, you might consider working into your assessment plan some way (even as a small percentage of the overall grade) to evaluate individuals' professionalism in-and-out of the classroom. What is available to you, then, is to speak communally about the importance of being respectful to one another, and affording everyone basic dignity.
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how to motivate student that programming will give bright future to them? some students in my class are leaving CS because programming is difficult and think that it will not give them bright future. how to motivate that students, that their interest is develop in programming and they become satisfied for their future. <Q> This might be a mistake, actually. <S> Everyone is different. <S> People like doing different things. <S> Programming isn't for everyone, nor is the wider world of Computer Science as a whole. <S> My daughter, for example, is perfectly happy as a Philosopher. <S> My son is perfectly happy outside academia. <S> Convincing someone to do something (a kind of advertising) may do them harm in the long run. <S> People spend millions of dollars convincing people to consume sugary drinks, to their detriment. <S> If you make the classes interesting, with interesting problems to solve, those who want to do it will stay. <S> Wish the others well and focus on those who want to work at it. <S> Some of us have found that group work (pair programming) is a motivator, introducing a social aspect to learning as well. <S> On the other hand, it is possible to make learning programming as dull and demotivating as learning multiplication tables. <S> I'll note that many things are hard. <S> Becoming an olympic athlete is hard. <S> Some people are willing to put in the work to do it. <S> For others, it isn't worth that effort. <S> Saying the "future is bright" is something you can't honestly predict. <S> Many things could happen that make it less bright. <S> The need for people specializing in CS might decline in future years as some processes become more regularized. <S> This has been the history of the world, actually. <S> One takes a chance on the future no matter what you do, so you might as well follow your own dreams, not those of someone else. <A> I used to teach adults (most well after college age) programming <S> so they could get jobs after a disability caused them to leave their previous job. <S> They were highly motivated to learn enough in one year to get hired. <S> What I focussed on was to make their learning free of unnecessary difficulty by pointing out the usual problem areas and trying to make my explanations direct, clear, memorable and interesting. <S> Your excitement about programming will interest them. <S> Some will drop out, but that is not your issue. <S> For any problems you cannot directly solve in your classroom, get help from the administration, and just focus entirely on your part, which is to teach and assist. <S> Usually later it can be changed when a better solution is seen. <S> That's the best advice I have for you. <S> Good luck! <A> Do you maintain contact with your former students? <S> I have a sizeable number of former students earning nice livings at places such as Apple, Microsoft, Google, Facebook, and YouTube. <S> Others are in great graduate programs. <S> Some are academics at places such as Stanford, UMiami, and UMaryland. <S> They are doing very well. <S> I use my network to benefit my current and former students. <S> It's quite powerful. <S> And it serves as a beacon to my present students.
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Be sure to explain that at times programming IS difficult and frustrating, and sometimes we have to choose a different way of solving a problem.
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How can programming skills be improved? I often take help from online videos to improve my programming skills, but I am not successful. Videos help me in debugging my code, but I am not improving my programming. Is there any other way through which I can improve my programming? <Q> The only way to learn a lot of things, maybe most things, is practice and feedback. <S> In a standard course (not online), the professor assigns some work to do - homework, <S> projects, .... <S> The professor then gives you feedback on it - grades, but hopefully more. <S> To learn on your own, you want to try to simulate this as much as you can. <S> So, to learn something, you not only have to see and hear about it, or even read about it <S> , you have to do it. <S> Moreover, you need some way to get feedback on the success of your efforts. <S> If the videos don't suggest projects then you will have to find them elsewhere, perhaps in a textbook. <S> Do a lot of small and large projects. <S> But then the feedback part is just as important. <S> One possible way to simulate that is to work with a friend in your learning. <S> Each of you does the same exercise separately and then exchange your work and each comment on and improve the other's work. <S> This isn't perfect, since the other person isn't an expert, but it is better than nothing. <S> You might even be able to use an online forum to get comments on your attempts. <S> The Code Review here, might work for you, though I don't know how welcoming they are of novices. <S> Be sure to see their "help center" for guidance. <A> You can follow below points according to your stage of learning. <S> If you done with basic syntax of any programming language then try to solve logical problems from various platform like hackerrank, codechef and many more. <S> Find out other techniques or methods to solve same problem in different ways. <S> If you done with logical question then try for Object Oriented Programming in that particular language. <S> After that you can go with Data Structures and Algorithms. <S> Try to implement Tree, Hash tables, etc. <S> After learning it's theory and syntax. <S> If you already a developer then you can try following suggestion. <S> Learn and try some new frameworks in you field. <S> Search and learn how to make you project scalable. <S> Search for adding security in projects and programs. <S> Participate in online hackathon and work with team. <S> Learn how to integrate like you are back end developer and one of your friend either IOT or app or something else then try to integrity with your platform or do project something like that. <S> Try reverse engineer code of someone else from online source and learn new techniques and methods. <A> Think of a problem and try to create a solution for it. <S> That forces you to look at new tools and techniques. <S> Another thing I do is revisit old code about once a year. <S> I go back to it to see if I can improve it with new things I've learned or to catch old miatakes. <S> When I can improve the code with things I've learned, it's encouraging because I can see my progress. <S> Also, there is a lot of info out there. <S> When I first started programming and wanted to improve, my biggest problem was that I didn't know where to start. <S> So, I looked at the Software Development Lifecyle because it cuts the process of developing software into different chunks > Planning, Analysis, Design, Implementation, Test & Integration, and Maintenance. <S> Then, I focused on learning about skills and tools for each of those chunks. <S> For example, when I wanted to learn about testing, I looked up "testing tools" and "testing methods" for software and tried out new tools and techniques whenever I started a new project. <S> Even if you're not specifically interested in software development, the skills you'll learn by looking further into each piece of that life cycle will help you. <S> For instance, let's say you write a lot scripts <S> and you look at the maintenance piece of the software development lifecycle. <S> By looking into maintenance techniques, you may find better ways to write code to make it more efficient and easier to maintain. <S> Essentially, looking at pieces of the life cycle helps narrow down the areas you're looking at a bit so you don't get overwhelmed. <S> Last thing: keep in mind programming skills don't always have to deal with just writing code. <A> It is just like learning how to ride a bike: by programming. <S> And by reading good (and also bad!) <S> programs critically. <S> Pick some (simple!) <S> problem to solve, have a go at it. <S> Look for some open source package that interests you, pick some "for newbies" task (if they advertise some). <S> Look around for more advanced data structures and algorithms (there are tons of lecture notes on those subjects available). <S> A bit of combinatorics/discrete math is a must for a well-rounded programmer.
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Improving programming skills can also include how you package your code, how structure/design it, or becoming familiar with how code is compiled. One good way to improve is to try new projects. Check out textbooks and tutorials for your favourite language.
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Suggestions for teaching selection sort with candy It's the end of the semester, so my students are pretty burnt out, and a bit of sugar might go a long way (plus, evaluations are around the corner ;-). I'm envisioning a tactile class where students would carry out the selection sort algorithm to sort an array of candy bars by length (or height, or size), by physically swapping candy bars. I would also have them write down the number of comparisons required, to get a better understanding of the time complexity. Ideally, every student (or pair) would get 4 pieces of candy. Can anyone suggest candy that naturally comes packaged into 4 or more different sizes? All I could think of is how Hershey bars can be broken along natural dividing lines into different numbers of squares, and how Toblerone bars also have natural break points. But both are chocolate and might melt. I'm embarrassed to admit I'm not much of an expert on candy bar types. <Q> Actually, I might suggest a slightly different tact: provide a variety of candies (small boxes of nerds, Hershey's kisses, and the like) and have them selection sort by preference order. <S> They can also sort by height, brightness, weight, or duration of the candy experience. <S> And as long as you're at it, you might first have them just sort it one of those ways <S> however they do it naturally, which can lead to a nice discussion about why we can't articulate what we're doing very well, but it's some sort of massively parallel selection sort. <S> Then you can do a number of sorts, culminating in your selection sort by preference order. <S> And at the very end, tell them all to look around at their neighbors <S> sorts to see if there are any obvious trades that they should be making! <A> This sounds like a bad plan. <S> Students won't learn much of anything by sorting four items. <S> Especially if they can "see" all of the remaining items. <S> They don't need a scan if they can visually select the next item. <S> I suggest that you sort tokens instead. <S> Then use the candy as prizes for various things, or just make it a sorting "party" where the yummies are free. <S> You need around 10 or so tokens for each group to get any sense about efficiency. <S> And you need to write instructions, especially for selection sort, that make it impossible to see all of the values at once. <S> One way is to use "poker chips" with numbers on one side. <S> When face down you have to examine them one at a time. <S> Make sure that whatever sort you use and whatever props that you don't make it possible to use non-algorithmic human capabilities like sight or touch to avoid following the rules. <S> Safety note. <S> Your profile says you teach college. <S> For those teaching youngsters, however, note that not every kid can handle sugar for medical reasons. <S> Other treats might be necessary. <A> My personal favorite way to teach sorting is with rubber ducks. <S> Since they sit with the number covered, the students have to pick up a duck to check the number.
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You could do something similar with candies if you wanted, where you write a number or letter or something on the outside of the package that will sit face down. I have a large set of ducks that have numbers on the bottom.
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How to introduce Kotlin in a Programming Languages course I'm teaching an upper-division college Programming Languages course, in which students have learned some Scheme, Haskell, and Go. Students' strongest language is Java, which we use in most of our courses. I have a free 75-minute lecture period. Any recommendations how to use that time? I can have the students bring their laptops. My reasons for wanting to introduce Kotlin are: Showing how the functional programming has been added onto an imperative object-oriented language they know well. Showing them how Kotlin uses a stripped down version of Java's syntax without losing expressiveness. Augmenting what they are learning in another class of mine, in which they are learning to program Android in Java. (That's why I chose Kotlin rather than Scala.) <Q> I think the answer to that depends on how you're structuring the course overall, and what Kotlin brings to the teaching of those ideas. <S> I know of three distinct approaches to an upper-division PL course: the "paradigms" curriculum (à la Sebesta's book), the "interperter/design space" curriculum (EOPL, Scott's "Programming Language Pragmatics", Louden, Turbak/Gifford/Sheldon, etc.), and the hybrid theory/implementation curricula (less common and few things in print: the Racket team, Norman Ramsey's adaptation-in-progress of Samuael Kamin's book). <S> Do <S> any of these describe what you're doing with your course? <S> What is it that Kotlin brings to the class that is not already represented by the other three functional languages your students have learned? <A> Just free associating here, actually. <S> The single session of 75 minutes is awfully short to actually have you do anything and then have the students learn anything. <S> So.... <S> First, flip the classroom for that session even if you don't generally. <S> Give them a week (more or less???) <S> to study Kotlin on their own, so that they have some sense about its syntax and main features. <S> For the single session, have them build a stateless server for some simple app using Kotlin in small groups, even pairs. <S> Making it stateless <S> lets you more easily stress the FP aspects (I think, but haven't actually tried it). <S> Note: still thinking about the stateless part. <S> Think about sending them something the evening before the session to get them thinking about what is coming. <S> Not a spec, though, since some will try to do too much beforehand. <S> One possibility that will help speed up the day's work is to send them a skeleton application the night before. <S> The task of the class will be to extend the skeleton to something useful. <S> I would probably do that if it were my class, actually. <S> Use the last quarter hour for a retrospective on what they learned and point them toward the future. <S> I don't know if this would be successful. <S> It might fail. <S> It might require modification for a future use. <S> Owen Astrachan at Duke as advocated that some small percentage of what you do in a course should be experimental so that you can learn more about what works and what doesn't. <S> But be prepared for it to fail so that students can learn even from failure. <A> I walked around pointing out similarities to and differences from other languages we studied. <S> The advantage of this approach was that students got to actively learn parts of the language. <S> The major disadvantages were not providing the history and not ensuring that all important concepts were introduced. <S> I plan to do those in a subsequent lecture, if time permits.
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You may have to give them an outline of what to focus on. What I ended up doing (partly because I didn't have much prep time for me or the students) was using the class period to have pairs of students work together through Kotlin Koans .
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How can I improve other programming languages while having command on one language As in computer science field we have to learn several programming languages like C++, Java, C#, python, php etc to complete our tasks and home assignments. However you are good in only one language. As I know all languages are related to each other at some extent, but it's difficult for me to remember syntax for all languages and doing different tasks for these to become familiar to these. How can I improve and learn other languages easily so that I can perform my assignments easily and in less time? If anyone can guide me.Thanks in advance <Q> Looking at Buffy's answer it's clear to me that I've understood the question quite differently, so I will set some context before I get to the point. <S> However you are good in only one language. <S> I think that this is too strong: it's possible to be good in several languages <S> if you use them all frequently. <S> However, I do know the feeling. <S> The main language used in my undergrad course was Java, and that was virtually the only language I used in the 7.5 years after graduating. <S> But for the past 9 years the primary language in most of the projects I've worked on has been C#. <S> Now when I revisit Java I keep typing string and getting compile-time errors until I correct it to String . <S> On the other hand, the key word there is primary . <S> One project was written in C# but used a code generation tool whose templates were in some weird Visual BASIC variant for which I never found documentation, and in addition had large and complex SQL stored procedures. <S> Real world projects often contain an unholy mess of different languages, chosen for good or bad reasons, and the ability to handle that is a useful skill to develop. <S> As I know all languages are related to each other at some extent, but it's difficult for me to remember syntax for all languages Supplement your memory. <S> Write revision notes as though you were preparing for an exam on the differences between the language: one side of paper (A4 or letter) where you list the most important mappings from your strongest language to the target language. <S> E.g. if your strongest language is Java then your notes for C# might include: import is using Method names begin with upper case <S> Map is IDictionary and HashMap <S> is <S> Dictionary Generic types are reified, so if you have a static field <S> Foo in a class <S> Bar<T <S> > <S> then Bar<string>.Foo is a different field to Bar<int>.Foo . <S> Also, use IDEs where possible. <S> It's much quicker to fix compile-time errors as soon as you type them than to wait until you've finished a unit and can attempt to compile. <S> Auto-completion for syntax is also getting quite advanced now. <A> Once you learn how to program with a given paradigm, learning other languages in that same paradigm should be fairly straightforward. <S> But if other tools than those you are used to are more commonly used with the new language use those tools as well. <S> But there are some subtitles. <S> For example, Java and Python are quite close conceptually. <S> But the differences require that you "think different" about some things. <S> For example, dynamic vs static typing is a really big difference between the two languages even though they are both OO languages at base. <S> In Java you write (I hope) <S> a lot of interfaces. <S> In Python it would be odd to do so, even if actually possible (with different syntax). <S> On the other hand, if you need to learn a language in a different paradigm, say a functional language rather than those you have in your list, then it might be good to go back to a "know nothing" stage and start with a good book intended for beginners in that language. <S> This is because the thought process in, say Scheme, is quite different from that in Java. <S> For example, it is a bit of a subtle thing to write a linear time process to reverse a list in Scheme if you are thinking like a Java programmer. <S> But the way that you do that task efficiently is a mind expander. <S> So, for a "similar" language, build something big with appropriate tools and watch for the tricky bits. <S> For a "different" language, start over. <S> Here "similar" means the same overall paradigm. <A> I teach classes that each use different languages: Python, C#, Visual Basic, Thunkable, Scratch, Alice, Small Basic and a few other odds and ends. <S> I am not good in any of them off hand, but I have a set of resource locations that will refresh my memory or show me the important features of the languages. <S> I learn how to learn languages. <S> I get the language syntax confused all the time switching back and forth <S> like I do <S> so I have to have samples handy as to how a particular task is done in a particular language. <S> I still mess up regularly but the kids all think I am a nut case anyway <S> so not big deal. <S> They live with it. <A> An effective way to learn another programming language is learning compared to the known language. <S> Ideally I think one language should be learned for each important paradigm: C / C ++ for imperative / objective paradigms, lisp / Haskel for functional paradigm and SQL for declarative paradigm - <S> the rest of the languages being a combination of these paradigms. <S> As for the syntax there is "Intellisence" or equivalent.
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One of the best ways is to write a large program in the new language.
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Through what basic programming language can beginners easily get the concept of programming? I have some students that are from medical background and have no concept of programming. So, which language I should teach to them to make their basic concept of programming perfect? <Q> Actually, this depends much more on the teaching methodology you use rather than the language. <S> But if you aren't a programmer yourself, it may be very difficult for you to teach them. <S> But, if I had to name a language that is (a) fairly modern and (b) fairly forgiving of beginners and (c) <S> widely used and (d) a useful tool for people with other interests, then it would probably be Python. <S> If you give up one or more of my criteria there are many other choices. <S> But the teacher needs to be proficient in the language and its use. <S> Programming is a way of thinking, not just knowledge of the features of a language. <S> I worry that, just because you are asking this question, that you may not have the required background to do a good job of this. <S> However, all is not lost. <S> I asked a question of my own here a while ago that might provide some guidance to you if you are, indeed, a novice programmer yourself. <S> See the question and at least my answer to <S> How do you teach something when you don't know it yourself . <S> The short version is you admit your lack of knowledge and learn it along with the students. <S> But first you need to find good tools and resources. <S> If you use Python, make sure you use V3 and not the earlier and incompatible V2. <S> It isn't any harder to start with the current version. <A> that is rarely used today <S> i.e. one writes X : integer; rather than int X; Generally pascal has a 'clunky' feel when compared with modern languages. <S> python - seems to be the popular choice <S> but there is a major problem in that you will have to use some kind of IDE. <S> tab and space space space space space look very much the same when a student's program won't compile. <S> The problem with the IDE is that the learner can get confused between language features and IDE features. <S> Python is also a functional programming language so better suited to learners who have done functions in maths. <S> Beginners will find procedural languages easier. <S> VB - I would not recommend VB as it is integrated into an IDE in which IDE features and language features overlap. <S> The programming paradigm of event driven programming is also bad for learners. <S> However it is easy to get quick results which motivate some learners. <S> C - My learners found C the hardest language but the C classes produced the best programmers in the end. <S> Some learners however found it difficult to make progress at all. <S> Maybe there is an argument for a project to develop a new language which is LR like C. possibly a subset of C or a version of C with additional string support and a simplified expression syntax! <S> Perhaps D fits that bill somewhat. <S> I would advise that the choice of environment and compiler is also really important. <S> You will want to concentrate on language not compilation issues. <S> Also forget to mention LOGO turtle graphics. <S> This is a surprisingly sophisticated programming language that allows an accessible introduction to the basic concepts of sequence, iteration, condition and function call. <S> I often used this for the first couple of lessons with total beginners to get the concepts behind programming embedded before moving on to a more 'serious' language. <A> Once upon a time, a lot of medical professionals picked up Mumps and Basic all by themselves. <S> Simple interactive command line Basic, not even requiring a programming editor or IDE to complicate things. <A> I think to learn programming language for beginner <S> then you have to tell him/her Java because it is used in Android Studio and in other tools. <S> And most important it depends on you how you teach him/her. <A> The best programming language for me is Java because it is now used in most of the programming tools. <S> I am also a Bachelor student and learning Java, and you are talking about the new one so according to this you can start from any programming language.
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The best answer might just be the language that you, yourself, are most productive in. I have used pascal, python, VB and C. Each have their own advantages/disadvantages. Because he/she know nothing about programming so can start their programming from any programming language but my prefer is Java. pascal - was designed as a language for learning programming but it is quite old and uses an LL(1) type syntax (left associative grammar)
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How to create webpage slides for teaching? I have PDF slides prepared in Latex. I would like to have all of my slides in a website where students can find all learning materials, animations, examples, etc. Do you have any experience with creating HTML/CSS/other from slides? Is there any framework you would recommend? Edit: I would like to write everything in HTML/CSS so I can add links and animations of algorithms in the future. <Q> pandoc can go markdown->latex <S> (beamer) too. <S> Not sure about going latex->reveal.js <S> but it could be possible. <A> One of our instructors at CSU does his entire course web site using Pmwiki , which uses a markup language. <S> If you follow certain conventions, it can be converted to a slide show in the browser. <S> For an example how this works, see https://www.cs.colostate.edu/~cs253/Spring19/ <S> This is a C++ course for students in the second year. <S> On the home page is a link to the slide technology used. <S> I believe it is java script that takes the HTML file and renders it in a slide format. <S> If you look at the Schedule page and click any of the links to lecture material, you will see a straight web page. <S> At the top left corner is a link that will render the page as a slide show. <S> You can advance through the slide show using the arrow keys. <S> One of the other instructors takes screen shots of the PowerPoint slides and embed them in the HTML page. <S> For an example of this style, see here . <S> If either of these interest you, I can put you in touch with the specific instructors. <A> Some options just put the PDFs on the site. <S> runestone — allows you to create interactive webpages, with programming code. <S> sozi — for creating animated slideshows from SVGs. <S> First use a $Tex$ engine that creates DVIs, then convert the DVIs to SVGs. <A> If you can get the slide deck into Google Slides you can publish to the web from there. <S> With your slides open, select Publish to Web on the File menu. <S> From there click on Embed and then the Publish button. <S> You'll get an HTML snippet that uses an iframe. <S> Copy and paste that into your HTML and <S> it'll look just like it does in the presentation. <A> Create a Beamer presentation using RMarkDown and you can easily knit to HTML. <S> Renders beautifully. <S> Reference: Rmarkdown Beamer Presentation
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pandoc can convert slides written in markdown to a html presentation using reveal.js . You can generate SVGs from $LaTex$ .
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What to do when pupil destroy lab equipment? I am teaching robotics at something like an afterschool but is free for everyone aged 12-19 years. The first problem I encountered was poor equipment and facilities, but I obtained some funds and I was able to buy laptops, new soldering irons, Arduino starter kits and more. I was reticent to put into use all at once and I opened up only one soldering iron to see how pupils would use it. Of course, we have safety instructions which include rules like do not degrade lab equipment and I repeated rules but after a few weeks pupils started to play putting soldering tip to wet sponge so water boiled and sounded nice to them, and what disappointed me was some holes in the soldering iron plastic case. I am the only teacher, I can't supervise all pupils at once and teaching here is consuming because everyone is at a different phase of constructing an electronic circuit for example. I was thinking to track the usage of equipment and with the very first occasion to punish the children by calling home to his parents or even to exclude them, but this seems unfair since everyone could damage equipment intentionally. What should I do to be able to have all of the equipment on the table but this kind of damage to not exist? I don't care if damage occurs when equipment is operated wrong or damaged by mistake. I don't want pupils to think of equipment like toys and play with them damaging them and workspace. Other cases of damage:- Cutting wires with wirecutter even if they don't need it- drilling holes in worktable with a drill bit- melting plastic with the soldering iron tip I know, partially it's my fault because I can't keep everyone at the same time captivated but damage should not occur. Thank you for attention <Q> How should I prevent damage to equipment? <S> Number each piece of equipment, assign each student (or each group of students) a number, and instruct students (or groups of students) to use only their numbered piece of equipment. <A> Some ideas, not all of which may be useful to you: <S> But you need to be aware that the age group is problematic, having little realization of the consequences of their actions. <S> The older students can be expected to behave a bit better, but even those have only the beginnings of adult sensibilities. <S> Find a way to get an assistant. <S> Paid or volunteer. <S> Have students work in pairs and make the pair responsible for their equipment. <S> You should probably assign the pairs so that Beavis and Butt-Head don't choose to work together. <S> Maybe exploit age differences to choose good pairs, with the more responsible students guiding the others. <S> While it is probably unrealistic that some students will "report" misdeeds of others, it is possible that you can encourage a few "influencers" in the group to positively change the bad behavior of others through word and action. <S> That is, have a "team" of responsible students speak to others when poor behavior is imminent. <S> Charge every student a "deposit fee" that will be returned at the end of the class if there is no damage. <S> If you can't asses damage against individuals, only a fraction of the deposit is returned after deducting a damage assessment. <S> But be prepared for an accurate accounting of the funds. <S> Exclude, with no refund, any student seen to be damaging equipment. <S> Contact the parents for any willful damage when noticed. <S> Have a session in which the students are actually asked to think up the worst thing they could do with the equipment. <S> The intent here is to get their "creative destruction" impulses out in the open but in a harmless way. <S> When they come up with "ideas" have them speculate on appropriate punishments for the various transgressions. <A> Before you give your students the equipment, make sure the documentation is right. <S> The safety instructions should be as clear as possible and easy to understand. <S> Also, aside from this doc, make your students and their parents (since some are under 18) sign another paper that states that any potentially intentional destruction of the equipment will be investigated by you, and those responsible for the damage will pay for their misconduct. <S> So be more strict. <S> It is not fair to you, who struggled to obtain those robots for the kids who really want to learn how to code them, for some kids <S> are really poorly educated by their parents and want to destroy the equipment. <S> It is also not fair to the others, who probably know how to take care of the robots. <S> You should also consider to name some responsible kids to be observers and to report to you how other kids treat the equipment. <S> If some kids are neglectful with the equipment, then stop giving them the robots for a period of time.
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Explain that each student (or group of students) is responsible for their piece of numbered equipment and they will face punishment if equipment is damaged. Get the parents more involved, with a signed paper from them that their child is responsible for damage and they will be assessed a fee if necessary.
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Shallow, broad and general introduction to programming I've planned a shallow and broad curriculum for a summer program (5 days a week for 2 weeks, 9:00 to 17:00) or sorts, and the flow of the subjects seems flawed. The students are gifted (not a prerequisite, but most of them are) highschoolers with either no background in programming, or very little background. The purpose is to interest them in learning programming. More specifically, to give them a taste of some aspects of various languages, hoping that each will find something they like and, being naturally curious, they might pursue the subjects they liked a bit more. The curriculum I have in mind is more or less: Using C : Intro to the simplest of things printf("Hello World!\n"); and the like most importantly, introduction to types . Using C++ / Java : very brief overview of OOP, just at the concept level "Things" are described in class es which have properties etc. Using JavaScript : Intro to functional programming. Again, just at the concept level "Things" are described with functions. and finally: Using python : finish with small tasks for them to get some hands on experience and things to show their friends As I see it, the main issue is, for lack of a better word, synergy . Subjects 2 and 3 seem highly disconnected. Moreover, I fear that for the students, the things they learnt in C and C++ will seem "pointless", since most of them will think that they don't use those concepts and ideas in the tasks in part 4. How might I bridge between OOP in Java or C++, with functional programming in JavaScript? Personally, I thought using Java's functional interfaces could work, but that would require teaching about interfaces, making the course far less "shallow" than it should be. Might there be a simple or neat "trick" to connect the two subjects? PS: Any other suggestions regarding the partial curriculum I outlined are also welcome. It's the first I've built from nothing <Q> The purpose is to interest them in learning programming. <S> More specifically, to give them a taste of some aspects of various languages, hoping that each will find something they like and, being naturally curious, they might pursue the subjects they liked a bit more. <S> Comparison of programming languages doesn't make sense until they've first mastered the basic concepts, so two weeks doesn't seem like enough time to get onto this. <S> I think you'd be better off taking one language which supports functional and OOP styles, covering both, and then maybe doing a small Rosetta Code presentation in the last day or two, with a handout which they can refer to after the course has finished. <S> I'm also not convinced that the students' curiosity will work that way <S> ("This idea of first class functions is fun: what can I do with it?"). <S> The difficulty with coming up with examples is that no two students will agree 100% on what things are fun and/or useful. <S> Games are a good bet for fun, although graphics tend to be complicated and you risk needing to dedicate lots of time to teaching/revising trigonometry and quadrature. <S> I'm not sure whether today's youth would find text adventures fun. <S> The concept of databases as useful is another reasonable bet: most people will collect something or follow a sport, and you can build and query structured data to enhance both of those. <S> Pick a language which has easy serialisation and you don't need to bother with "real" databases (although maybe mention them in the handout). <S> Although I've never used it myself, Swift looks like a reasonable teaching language if you want compile-time typing. <S> From looking at examples on Rosetta Code it seems to have clean syntax and support imperative, functional, or OOP styles. <A> With two weeks, you'd be better off focusing on a bit. <S> If you are teaching C++/Java, why Python? <S> I would choose only one of those three languages, as they are all fairly similar. <S> Alternatively, if you wanted to do some OOP, have you considered using C#/Unity? <S> It results in some quite fun projects right out of the gate, and they are working in a fully professional environment as they begin. <S> I suppose with only 10 days, I would think about either doing web development or Unity, and I would spend a bit of time working with GitHub in either case. <S> Two weeks just isn't a huge amount of time, and students appreciate coming out with a few firm skills that they can comfortably use. <S> Both web dev and game development lend themselves towards extensible projects so that advanced students can zoom ahead and learn more, while slower students can actually master some basics. <A> I agree with several of the replies. <S> You are biting off more than you can chew. <S> What you are planning for in 2 weeks is more than I would take on for a semester <S> no matter how sharp the kids are. <S> I have been teaching high school programming and CS for 30 years <S> so I know kids. <S> Draw castles, houses and tesselations. <S> Great for teaching fundamentals of programming in a fun way for kids. <S> Then I would go to Python with Visual Studio Code. <S> If you have any budget buy some Lego EV3 robot kits and use the VSC extension for the EV3. <S> The Unity/C# is another thing that is fun. <S> Coding would not be an emphasis, <S> the C# used in Unity is pretty high level, so the kids would be doing a lot of cut and paste coding <S> but there is nothing wrong with that. <S> The idea of a summer camp is to have fun, not be buried in tedious. <S> Nine to five is going to be bad enough. <S> Forget the C/C++/OOP. <S> They can do that when they hit college. <A> You need to pique their interest. <S> That means doing some sort of GUI work, perhaps creating a little game, store and retrieve some data. <S> I'd recommend using Python: <S> simple syntax, has all sorts of bells and whistles (OOP! <S> Lots of libraries for all sort of stuff, even symbolic math). <S> Please don't try to show them several languages! <S> Somebody said "learning the first language takes a year" (traditionally, "Programming" and Data Structures"), "the second six months, then you learn a language in a month". <S> That coincides with my experience (as long as the languages aren't too different!). <S> But that first year is required, and it is hopefully the same language. <S> Different ways of expressing, e.g. a loop, just confuse newbies for no purpose.
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Have fun with one or two languages instead of dabbling in several. For beginner programmers at the high school level I would go with Small Basic and do a bunch of turtle graphics. I think that the hook should be that programming lets you do things which are fun and/or useful.
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Python IDE for beginners With a bunch of colleagues we will start learning Python together. I'm a programmer, but I'm new to python. Most of my colleagues know some VBA, but are generally new to programming. What IDE do you suggests? Features I'm looking for: simple interface, some debugging features, autocomplete, inline help, intlisense. Thonny IDE looks promising, super simple to install with bundled Python interpreter, it does have autocomplete, but is nowhere near Visual Studio levels of inline help (like intellisense or pupup tooltips etc.). Any recommendations? <Q> I'm not a fan of full IDEs for beginners. <S> A few years ago I switched my first year students (Java) from NetBeans to an online tool without any autocomplete or helpers for most assignments and found that they've gotten way stronger at writing code. <S> I think the automatic stuff that helps out while programming becomes a crutch for newbies. <S> Our intro teacher, who teaches Python, really likes Idle for his first year students because it's so simple. <S> I've also used PyCharm with second and third year students, and really like it. <S> It's what I personally use when I'm writing Python code. <S> The free community edition is plenty for classroom use, but they've also got free licenses for students, teachers and classroom labs if you wanted to use the pro version. <S> a lot of their mistakes are because the tool told them to <S> So much this. <S> When NetBeans highlights something in yellow, students feel that they have to click on it and follow the programs advice even when they have no clue what it's saying. <A> Visual Studio Code. <S> Easy to set up and designed to be simple. <S> VSC is more versatile. <S> Eclipse is a management pig for beginners. <S> You have to learn Eclipse along with learning Python. <A> My preference might be different from most, but some of the things you seem to be asking for are inconsistent. <S> For me, an "IDE for beginners" is one that doesn't need to be abandoned for a different language. <S> Once you spend the time to learn it, you can adapt it to anything. <S> For me, also, that means a professional level IDE like Eclipse, which I now use for everything. <S> But Eclipse isn't, technically, just and IDE, but a plug-in platform. <S> You can plug in just about any language, but you can also plug in UI elements that can tailor it to beginners, say, showing fewer elements - or more. <S> But anyone who can handle Visual Studio won't be put off by Eclipse. <S> It supports just about anything you could want as a programmer, including unit testing. <S> And, like riding a bicycle, once you know it, you know it. <S> Note: <S> I'm not affiliated with Eclipse. <S> Just a long-time user. <A> I start my students on Blockly for coding, as I find it is really useful to develop some algorithmic thinking. <S> There is a developer section where you can create code with blocks (like Scratch) and "see" the equivalent Python/Javascript/Lua/PHP/Dart. <S> We use NotePad++ for html and css but will swap to Atom.io next year (most like Sublime Text but free). <S> When we start coding in Python, we use the same text editor for this as well, and so the class must use the terminal/shell to navigate to the file location and run their code. <S> As other answers suggest, there are no supports in Notepad++ such as autocomplete or autoindent. <S> Learners really have to get used to doing it for themselves. <S> After a few weeks, I introduce the PEP8 check . <S> There is also an auto-correct version here <S> but I don't show this until they have worked on fixing some code in class. <S> We are waiting to have Thonny installed as it looks like the best IDE for Python Beginners imho. <S> I know learners last year struggled with PyCharm, which is my own preferred IDE. <S> There are many great IDEs out there, but from my evaluation of them all, I have settled on Thonny as a great "beginner" IDE and PyCharm as my preferred "intermediate" IDE, although there is little difference with Eclipse or Visual Studio Code imho. <S> Hope this helps! <A> Why would you use an IDE anyway ? <S> You can go directly with command line, either with Linux or Windows, you'll just need a text editor and a command line terminal and here you go. <S> (I recommend Sublim Text) <A> Notebook to be a great way to develop Python (or R). <S> It lets you develop in a “web page” and everything displays in a browser. <A> I would really recommend Pyzo(formerly known as IEP) especially because of these three reasons: <S> it's lightweight, so it works with any laptop if it is fast enough for the operating system <S> it's simple and NOT too packed with features <S> it includes an IPython console which uses the major advantage of interpreted languages that they are, Hello Captain Obvious, interpreted on the fly
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I used to use PyCharm and PyScripter with good results. Eclipse is great for pros. If you’re interested in developing algorithms, I’ve found Jupyter
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What is a good introductory language for high school? I'm teaching introductory programming for high school. Back in the day, when I was starting out, DOS and Unix terminal prompt was normal UI, and console apps would spark kids interest. Now, on the other hand, kids grow up on the web, and a console program would look quite uninspiring . On the other hand, I'm not sure if JS (which is the web language) is a good introductory language. It's got a lot of gotchas which can confuse beginners, and I was thinking that a language like Python or Go would be a better introductory language. On the other hand, they don't have much of a front-end, and I don't want to teach two languages at the same time. What do people suggest? <Q> If Advanced Placement CS is in their future, then Java is probably the best language choice as it is still used in APCS. <S> There are also a lot of resources for Java development that also permit graphics based insight. <S> The course probably wouldn't be about developing for the web, though. <S> But because of the APCS link there are a lot of resources intended for novice programmer development. <S> One resource (Java) <S> that is very useful for such students, and has a lot of project ideas built in to it <S> is Greenfoot , which uses a rectangular grid to place visual representations of objects and lets them move an interact according to the student program. <S> There is also a dedicated teacher resource for it: Greenroom . <S> It has additional greenfoot projects and a forum for discussion. <S> It has less syntactic load. <S> But the set of resources for novices is a bit more scattered. <S> But any programming that uses some visual metaphor is better for student understanding than just numeric programming. <S> It needn't be web based, but should be graphical. <S> Games are pretty good for this provided that they aren't just textual. <S> Any simple board game can provide a nice way to visualize what a corresponding program needs to do. <S> But, one way to avoid the two language issue in web development is to have the students build only the back end or only the front end with you providing the other. <S> It also defines a set goal that students can program toward. <S> The part you build can be in a different language than that used by the students, of course. <A> I agree with Buffy that a great way to think about it isn't "language", but "language + library" or "language + provided code". <S> David Malan does a masterful job if this in his CS50 course, and anyone can see these labs. <S> Those labe are impractically large-scale for someone without his staffing , but they give a sense of what is quite exciting. <S> Buffy's recommendation of Greenfoot is absolutely excellent. <S> I have colleagues who use it this year, and they described it as one of the best pedagogical tools they've ever encountered. <S> Unity allows you to create exciting projects from Day 1, and gives you an entry point into C#. <S> Godot is great if you'd like a more Python-like language. <S> Finally, remember that these are merely starting points. <S> Once the kids are up and running in the basics of the language (and enjoying themselves), you can take them out of the starting environment in almost any different direction. <S> If you find it interesting, and present it with enthusiasm, they will usually be with you. <A> There is no better first line-code language than Small Basic. <S> Lots of nice simple projects for beginners. <S> Python and especially Java can be very intimidating to beginners and will scare away many kids. <S> Small Basic is a step up from Scratch. <S> There are a lot of beginner routes out there to get kids started. <S> Another excellent language is Alice. <S> I have my programming students build a scene from Shakespeare using Alice. <S> If you have access to Lego EV3 robots Small Basic has an extension for them. <S> There is also an EV3 extension for Visual Studio Code/Python if you want to step up to a more difficult language. <S> Be careful what you start kids off with. <S> Throw Python or Java at them you retain maybe 10% of the kids for the next class. <S> I introduce Python in the 3rd semester. <S> By then the kids are not intimidated by programming and problem solving techniques. <A> <A> When I took a programming course in highschool I liked the programming projects that forced you to solve a puzzle. <S> They don't have to be graphical but can demonstrate programming utility and really make you think. <S> E.g.: <S> Solve the Tower of Hanoi problem. <S> Write a tic tac toe game using text as the graphics. <S> Write a program to solve your math homework. <S> Find large prime numbers. <S> Then you could rank them by difficulty and say, "Do two easy tasks, or one medium task. <S> " Puzzles kept me entertained and showed me the utility of programming. <S> My examples are terrible, but it only takes a quick search for "programming puzzles" to get many more examples, then let the students pick their favorites.
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You might want to consider Visual Basic or Delphi where it is simple to create graphical user interfaces. Otherwise, Python is a pretty good choice for beginners. I would also recommend looking into game engines.
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A real world example for the divide and conquer method Can someone give a real world example for the divide and conquer method? For example, I've heard the boomerang used to explain the idea of a loop back address. What is a real world example we can use to teach students about the divide and conquer method before going to more complex algorithms? <Q> Back around 1985, Susan Merritt created an Inverted Taxonomy of Sorting Algorithms . <S> The idea is that to sort an array you have two phases, the split phase and the join phase. <S> She divided the various algorithms into two types easy split/ <S> hard join and hard split/ <S> easy join varieties. <S> Merge sort is of the former type. <S> Quick sort is the latter. <S> But all sorts, envisioned in this way are divide and conquer. <S> Her original paper (part of her doctoral work) is a wonder and worth exploring by any CS teacher. <A> It's no coincidence that this algorithm is the classical example to begin explaining the divide and conquer technique. <S> I am not sure at what level you teach, but your students should be comfortable with both recursion and inductive proofs before venturing far into this territory. <S> Coincidentally, there is a list of divide and conquer <S> algorithms found here . <S> It's a pretty long list, and might have cast too wide a net. <S> I'm not convinced that I agree that all of the algorithms are genuinely divide and conquer. <S> However, it could be that upon closer inspection, they are. <S> In any case, it's a great starting point to find algorithms to present to your students. <S> Just be sure that you can clearly explain the central divide/conquer/combine throughline for any algorithms you choose to bring to your students. <S> This area of algorithms is full of traps for unwary beginners, so your students will benefit greatly from thought and care put into your presentation. <A> These sorts of patterns are a bit tricky in real life. <S> In nice easy computer-science land, every step is the same, just smaller. <S> Merge sort is clearly the ultimate easy example of this. <S> In real life, we tend to break things up along useful lines. <S> If we're sorting change, we first divide the coins up by denominations, then total up each denomination before adding them together. <S> In war, we divide an opponent into pieces which cannot work as a cohesive unit, then crush them. <S> We see this in real life more often than blind divisions because we, as humans, know we can divide along useful lines. <S> The closest <S> I know of that is quicksort's attempt to find a middle index to partition with. <S> One thing I find tricky about these divide and conquer algorithms is that they look like an infinite regression. <S> You keep proving you can sort lists as long as you can sort smaller lists.... which you know you can do because you can sort smaller lists... <S> so on and so forth. <S> Infinite regression is a serious faux pas in modern logic, so I think people may get confused by that. <S> Then again, all may be for naught, for it is quite clear <S> the best use for divide an conquer in real life is to put together a thrilling Hungarian dance . <A> If you want to divide a long loaf of bread in 8 or 16 equal pieces, generally people cut it into two equal halves first and then cut each half into two equal halves again, repeating the process until you get as many pieces as you want - 8, 16, 32, or whatever. <S> Almost nobody tries to divide the loaf into 8 pieces all at once - people can guess halves much better than eighths. <A> MergeSort is fairly easy to implement in Python <S> and it's a straightforward divide-and-conquer algorithm. <S> You keep splitting the collection in half until it is in trivial-to-sort pieces. <S> This splitting reduces sorting from O(n^2) to O(nlog(n)). <S> Second example: computing integer powers. <S> if the power is even, square base and integer divide exponent by 2. <S> If it's odd, do the same and multiply by a factor of the base. <S> This algorithm is O(log(n)) instead of O(n), which would come from computing an integer power with a simple loop.
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The simplest example that still bears enough complexity to show what's going on is probably merge sort. When we put together a puzzle, we divide out the edge pieces first, put them together, then build the rest of the puzzle on that. Showing that "if I can sort a list of length n, I can sort a list of length 2n" would be the more traditional mathematical induction approach.
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This question is for anyone who has read Introduction to Algorithms by MIT press 3rd edition - Exercises, how to make them easier? I'm a student at a liberal arts college who has recently been taking classes at a tech school due to our schools cross-exchange program. I did not do well last semester, so I have spent the summer educating myself. I learned C by doing all of the exercises in the previous book I read. Now I'm doing something that a professor told me to do in a tech school, study algorithms in C. So, I bought a textbook Algorithms in C. But this textbook is asking me questions about algorithms I don't fully grasp how to answer, so I cracked open Intro to Algorithms 3rd edition and resolved to get through Chapter 3 at least so I know how to analyze algorithms properly. Here is the thing, I have been reading textbooks all summer, this is the third book I have gotten to, and it's difficult. It's difficult because, I don't understand how to problem solve the questions in the book until I get to the answer key on the internet. This isn't good, and I need a method or a way of seeing this properly. Without the online answers guide, I would have never solved most of the questions in chapter 1 and 2. I understand them now, but I'd rather be able to get through them on my own. Another question: Is it important to do every exercise in this book? <Q> While it isn't necessary to do every exercise in a book, it is important to be able to do every exercise in the book. <S> Similarly, while it isn't necessary to write every algorithm, it is necessary to be able to write every algorithm. <S> But learning is another issue. <S> Reading alone isn't enough to learn something. <S> I think you already understand that. <S> You need practice with what you've read to make sure that you have a deep and long lasting understanding of the topic. <S> So, as you've already discovered, you need to do a lot of well chosen exercises. <S> But even that isn't enough. <S> You need feedback on your attempts. <S> You need someone to look at your work and tell you where you have done the right thing and where you need improvement. <S> I'm not sure where you will be able to find this feedback. <S> That is the real value of taking courses - the feedback is built in. <S> Unfortunately not every course gives enough feedback, of course. <S> If it is just grades, it isn't enough. <S> You need it pointed out where and why something didn't work so that you don't build bad habits. <S> (Reinforcement without feedback can be counterproductive). <S> Perhaps there is a professor who would be willing to look at your work. <S> Perhaps you have another more advanced student available. <S> Some people create study groups to give feedback to each other. <S> Even an online "buddy" who can evaluate what you've tried. <S> And note, also, that having the answers available isn't really sufficient feedback until you learn how to find the misconceptions that led you to the wrong answer. <S> It is little misconceptions that can throw you off and someone giving good feedback can help you get the insight to avoid them. <S> Find someone. <S> As for making it easier , only reinforcement, feedback, and time will do that. <A> I would add to Buffy's completely wonderful answer only this: do not fret too much if you don't always get the questions on your own, particularly in a self-learning context. <S> Many of these algorithms took brilliant people years to come up with, and while they have now been well established and boiled down to their essentials, do not be fooled; they represent deep thinking and deep mathematical truths. <S> If it takes some time to absorb them, that does not mean that you are doing poorly. <S> Think of your study as gardening, and your consistent efforts will be rewarded over time. <S> There is no requirement that you learn everything deeply in your first pass. <S> Just be patient with yourself, and learn your lessons well. <A> Let me offer you another perspective. <S> Since you study at a liberal arts college, I presume you are not majoring in computer science. <S> So, the book you are talking about (Cormen's) isn't really a simple one. <S> It is intended for CS students with a certain background that you might lack. <S> There is not much profit in trundling through a difficult book if you realize how solve an exercise only after seeing an actual solution. <S> Yes, perhaps, you might be able to learn some algorithms by heart, but it looks like algorithms are not becoming a part of your natural thinking process. <S> When you see a solution, you can understand it; but you can't come up with your own ideas since this "algorithmic thinking" is not a part of your normal daily cognitive process. <S> Both "Algorithms and C" and "Intro to Algorithms" are detailed books in part intended to serve as reference material. <S> The latter book also contains a fair bit of maths. <S> I don't think you are supposed to memorize every single procedure described there: it should be enough to know what is doable, what is the general idea of a solution, and how complex a particular algorithm is. <S> I understand that you need to prepare for an exam, but if you had more time, I'd say that the "proper" way of understanding algorithms is to pick up a much simpler book (such as Grokking Algorithms) and try solving simpler problems entirely on your own. <S> If you face an easy task, you should be able to figure out how to solve it, and then you'll be able to appreciate other, more efficient ways of achieving the same result.
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Comparing your solution with a more efficient solution is more helpful for self-improvement than just checking the answers, I believe. Reinforcement and feedback are the key to learning.
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Explain to someone that programming isn't just all "if"s and "else"s I have a friend who, in his mind, has the wrong image about programming. Whenever I mention that programming is fun and that one can enjoy it very much especially if they like solving problems (both math and algorithm related), he stares at me and repeats "if this then do this.. what's so hard or fun about writing that?" and that's just annoying. It is as if one would say " ah well, maths.. 1+1 = 2 there u go! ". Is there a way I can make him paint a better picture in his mind regarding this field? About 10 years ago when he was younger, he did try basic programming and that's what I believe he is basing his judgement on. (Not sure if this is the right place to post this but let's see... ) <Q> You may have to resign yourself to not "winning" this argument. <S> From what you've written, this is what I suspect is the real answer. <S> For what it's worth, he's not, strictly speaking, wrong . <S> Data storage and branching are a huge portion of what computers actually do. <S> But if you still want to attempt to capture him, you might point him towards image recognition. <S> Sure, it's "if this then do this" in theory, but two different images of birds will share not a single pixel in common, so how do you teach a machine that can only look at one pixel at a time to identify one? <S> " <S> Computer Science is no more about computers than astronomy is about telescopes." <S> -misattributed to Edsger Dijkstra <S> Of course, even if he concedes the complexity of the problem, that's still a ways away from seeing the joy in trying to solve it. <S> I'm not sure there's truly a way from here to there if he's not interested in taking an honest look. <A> What about music?A C white note on a partition means a specific frequency for a specific amount of time. <S> And a partition is just a sequence of such commands. <S> Looks pretty dull to write such a thing, no ? <A> Depending on the person there may be different approaches, here are a few: <S> Listen to them, ask them to tell you about their experiences. <S> Consider different programs that can be written, to solve a problem that they may have. <S> Solve a problem for them. <S> Puzzles <S> : Show some programming puzzles. <S> Prove that you can write any program <S> (is Turing complete), without conditionals (this also rules out recursion, except infinite). <S> (I have done this) <S> Prove that you can write any program <S> (is Turing complete), without iteration: You will need conditionals, and (at least tail) recursion. <S> Show alternatives to conditional code: tables (conditional data), polymorphism (Lizcov substitution), <A> I don't really think it's your job to convince your friend that programming is fun. <S> But I'm going to answer because I think there are other situations where presenting the "fun" parts of computer science has benefits, <S> e.g. when teaching an introductory class. <S> Focus on the end result rather than on the process. <S> Which examples you use depends on who you're talking to. <S> You might talk about creative coding or generative art . <S> You might talk about game development or procedural generation . <S> You might talk about artificial intelligence or healthcare or scientific simulations . <S> You might talk about art, or sports, or dance, or music, or prose. <S> Show your audience examples of interesting things that were created with code. <S> Then show them how to do it themselves. <S> See also: How to teach a person to enjoy programming? <A> Here's one that is recent (and in the news): Machine Learning. <S> Alpha Zero is a program developed to learn how to play chess based on only the rules of the game. <S> It learns by playing games against itself and evaluating the positions and results of the game. <S> This is revolutionary and will change the face of how we interact with computer systems. <S> Professional chess players are now learning from the games that Alpha Zero has played. <A> Sadly your friend sounds to be a product of current bad programming practices he probably also thinks that program is just about learning a language . <S> so give your friend this problem to solve: old fashioned phone keypad had letters to translate into numbers such that you have phone numbers like 1 800 call me <S> so write a function that translates any letter into its corresponding number on the phone keypad without using any if statement (or switch,etc). <S> .. <S> this is what real programming is about. <S> using too many if statements is typically considered bad programming. <S> sadly proper software engineering principles are being missed these days in order to turn programming into programming for dummies but many corporations still know the difference
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Obviously your friend is using a bit of hyperbole, and in truth, however annoyed you may be by his blithe dismissal of our entire field, he may not be open to being persuaded. Tell them about your experiences (Don't work about difficulty, it is just a story). Instead of focusing on the act of writing code and trying to paint that as a fun process, focus on the cool stuff you can create with code.
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Learning to program a Cell Phone Somebody wants to develop applications for his cell phone in Java. He does not know programming and he does not know Java. Should he start learning Java on his cell phone or would he better off learning how to program Java on his PC? <Q> Should he start learning Java on his cell phone or would he better off learning how to program Java on his PC? <S> These aren't your only options. <S> IMVHO, Java, especially Android, has a pretty steep learning curve. <S> I would recommend starting with something like Processing to learn the fundamentals, and then I would use those fundamentals to transition to core (desktop) Java. <S> When you have a good grasp on that, then I'd move to more advanced topics like mobile development. <S> Since you've tagged your post with curriculum-design , here's how I would design a curriculum. <S> I would split it up into at least 3 different courses: <S> Course 1: <S> Intro to Programming. <S> Use Processing to introduce the fundamentals: functions, variables, loops, control flow. <S> Course 2: <S> Advanced Programming. <S> Use Java to introduce OOP, inheritance, data structures, algorithms. <S> (In the US I believe this is the standard AP CS class?) <S> Course 3: Mobile Development. <S> (After course 2 you can branch out into many topics, not just mobile development.) <S> That's my two cents, but I know other people approach it from other directions. <S> For example I know many folks teach web development first. <S> And Google has at least one curriculum that uses Android to teach the fundamentals. <S> The question of how to learn the fundamentals of CS has been asked here a few times before, so I'd recommend starting with a search. <S> Here are a few posts to get you started: <S> How to teach a person to enjoy programming? <S> Programming language for teenagers Order to Teach Topics in an Intro Programming Class Explain to someone that programming isn't just all “if”s and “else”s Programming languages specifically designed for beginners Using Processing as an entry point in an Introductory Course <S> There are many potential paths through computer science education, and I think the best thing you can do is try a few out and see which one works best for you. <S> Also, like Buffy said , you probably don't want to program on a cell phone. <S> Even if you're programming a mobile app, you're almost always programming on a computer, and then exporting the app to a phone. <S> Shameless self-promotion <S> : I've written a series of tutorials that take you from Processing all the way through core Java and onto web development and Android, available at HappyCoding.io . <A> I don't see any particular reason that using a mobile device API would be any worse than learning Java on a PC. <S> But an environment on a desktop that uses simulation of the mobile might be a good way to work. <S> Note that programming for the phone is different from programming on the phone. <S> The latter is probably restricting (small screen, terrible keyboard, ...). <S> A more direct, rather than a more circuitous route to a goal might be good, actually. <S> But if the goal is Java generally, with its wider API, then programming on a phone would be limiting. <S> Also, programming on the desktop with emulators may ease the porting problem so that the code runs on more than one phone. <S> The iPhone doesn't support Java, for example, but a desktop environment might, in principle, be able to translate for that device. <S> But note that I don't do this myself. <A> I presently teach an app building course at high school. <S> I did a lot of research as to what platform to use to build the apps. <S> For Android Android Studio is the big gun. <S> It uses Java. <S> AS has a killer learning curve and requires nice computers. <S> I am not good at Java (I teach Python) and the school has junk for computers. <S> Keep digging. <S> I found Thunkable. <S> Flat learning curve and runs great on junk. <S> The kids can actually build decent apps for both iPhone and Android. <A> In my opinion learning to develop apps as a first step seems to have a quite steep learning curve. <S> Maybe start with console applications first and get into programming slowly but steadily! <S> Don't try flying to the moon when you don't even have a paper plane! <S> And of course Buffy mentioned a lot of important points as well. <A> I think there is a subtle point missing from the concept of programming. <S> When you stop to think about it, teaching someone to write an app for Android or iOS is not just programming in Java. <S> Small steps make long journeys. <S> Writing apps may be the goal but first you would need to have a foundation in Java. <S> Then you can build on that by learning the Android API. <S> In reality, what you are really doing is writing an extension to the android OS. <S> Here is how I see things… <S> "APP" EXTENDS "ANDROID" EXTENDS "JAVA" EXTENDS "C" EXTENDS "ASSEMBLY" EXTENDS " <S> MACHINE CODE" <S> EXTENDS "HARDWARE" EXTENDS "HUMAN" To learn Java <S> I think it would be easire to start someplace that does not require the odd (to a new person) expanation to take a bunch of steps not related directly to Java in order to learn Java.
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If your goal is to teach Java then building apps is the hard way to go.
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A category to classify expressions, statements and blocks I was teaching an intro to Programming class, full of social scientists. After explaining that the basic building blocks of a program are called tokens, I took them through Keywords, Identifiers, Literals etc. I was asked a question. And have been reading to find answers in books and online. They asked if we group the basic elements of a program under the word "token", then what word groups the other program elements. e.g. expressions, statements and blocks, that are derived from tokens? Help with a reference or a term that classifies these constructs as a group. <Q> This is a surprisingly complex question. <S> In many languages one can distinguish between commands and expressions . <S> A command is something that changes the state of the computation. <S> An expression is something that returns a value, but doesn't change the state. <S> This is actually a good mental model even in languages that can confuse the two ideas in small or large ways. <S> Some languages consider statements to be commands, but in C, for example, an assignment statement is also an expression that has a value equal to the value assigned to the variable on the left. <S> That may or may not be the value of the expression on the right, actually, as when a short is assigned to a long. <S> Likewise blocks can either be commands or expressions in most languages. <S> A function block is an expression, returning what the function returns (more or less) <S> but it can also have command-like properties if it changes the state generally, say by modifying a non-local variable. <S> But the if-clause in an if statement is usually just a command. <S> So, I don't think there is a single unifying category for all three of your items, but the distinction between commands and expressions is useful. <S> It is useful for another reason as well. <S> In C a "function" can return a value or not (void functions). <S> But programs are easier to understand if a function that returns a value does not also change anything in the non-local state. <S> Then functions when invoked will be either expressions (the value returned) or commands (the state changes) but never both. <S> But C also has a distinction that even command-like functions often return an error state indicator, zero <S> if there are no errors. <S> So common practice gets in the way of the useful rule in the paragraph above. <S> C++ can use exceptions instead of error codes, of course. <S> But in more "modern" languages, the distinction between expressions and commands is maintained with a bit more clarity. <S> Java, for example. <A> People create categories as needed to manage complexity. <S> A language designer has defined syntactic & semantic things--including categories of things--relevant to their purposes & so can anyone--specific or fuzzy. <S> It's unhelpful & misconceived to expect that somehow categories are out there to be uncovered or that everything must be in a category or that any pattern one gets a glimpse of is evidence of a category out there to be uncovered. <S> This is a case of the fallacy of Reification. <S> Of mathematics, Kronecker said, "God made the integers; all else is the work of man." <S> In programming languages, expressions, statements and blocks are categories of language strings or trees with associated grammar production rules. <S> Relevant helpful larger grouping for these are things like definitions, programs & compilation units. <S> But those are ad hoc per the language. <S> Generally, what helpful syntactic categories there are is driven by what helpful semantic categories there are. <S> Sadly, programming languages' semantics are typically poorly taught. <S> Even though its semantics are the raison d'etre of a language. <A> I just learned quite a bit from Buffy's wonderful answer! <S> I would only add that a token is simple the smallest unit of text that carries semantic meaning to the compiler. <S> Thus, int func(int input) <S> { has 7 tokens (four word tokens and three symbol tokens). <S> An escape character in a string such as \" , then, is a note to the tokenizer. <S> How they are later grouped and interpreted are decisions for later in the compilation process, based on the contents of each token. <S> I don't think that I would try to relate token to either of your other terms, as the relationship is in no way straightforward. <S> That depends on the contents of the tokens themselves.
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Expressions can be tokens (such as 42 ), or can be groups of tokens ( x + 5 ).
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How might I structure an assignment with two "levels"? I've been mulling this over for several hours, and have looked at a tangentially related question here . That question was about making a task more challenging for a "more confident" learner. I have what I call "hacker versions" of programming tasks in code, such as producing a GUI version of RPSLS rather than the CLI style we do initially in class. There were no extra points. Here, I was wondering can I/ should I have a "simplified" assignment that would be "easier" and be weighted "downwards". The class have previously completed a use case (table and diagram) for accessing a course on Coursera, so they had to identify a range of use-cases, including identifying 'extend' and 'include' cases. I teach a course (introductory) in software architecture at roughly the level of first year in third level. The outline for the assessment (1 of 8 summative assessments) states "Derive a test case from a provided use case". Examples in class were the "classic" ATM test-case, as well as a vending machine and an e-payment site. At the same time, in another module (code) we used the doctest module (Python) with the testmod() function to check test cases in the docstring. I created a simple use-case diagram for submitting an assignment on Moodle. There are a number of test cases that this prompts. I am/was considering another (perhaps simpler) use case based around the type of code we did in class and this prompts several types of exceptions and even an alternate flow. I wrote some code here as an example of what I am considering. The test-case template would have to be completed by the learner to show that they have considered all the possible problems that can arise... for example, a negative int should raise a ValueError, using two strings should raise a TypeError and so on. I did a sample test-table in class based on a area_circle(rad) function, and so I was thinking this might be an option for the "less confident" (as described on CS50 pset2 referenced in the first link) but as I think about it more, if the learner completes this then they achieve the learning outcome, and I should NOT have it weighted to be of less worth than one which could be considered more difficult. Now, after all this, I am inclined towards giving both options to the class, with no differentiation between points, but I still wonder: 1) Should I offer both options? 2) Is there ever a case for creating an assessment with "less worth" to allow a learner achieve some marks, or if the "lesser" task demonstrates that they meet a learning outcome, is this unfair? Has anyone done something like this (easier version with less points) I know I could have been more succinct in my question, but appreciate any feedback you can give. Thank you. <Q> I didn't go through all the details, but can share an experience. <S> I once taught a database course to a bunch of good students. <S> The course covered lots of things such as relational theory as well as the internal structure of the data in such a database system. <S> The harder one was to implement B+ trees if I remember correctly. <S> The easier one had something to do with hash maps or such. <S> The instructions were that you could choose which, but if you'd already in your life built a hash map then you would find the easy one boring and the other would be interesting. <S> A surprising number actually did the harder assignment. <S> They were weighted and graded the same. <S> There was no benefit to the harder one other than learning. <S> But the students were eager to learn and that made it possible. <S> But I'd recommend against a system in which only low grades could be earned from a simpler assignment. <S> I think that is psychologically damaging. <S> Like deciding to fail before you even start. <A> My larger assignments are often tiered. <S> There is a minimal expectation of the work to be done and for this a student can earn about 85% of the total score--right in the middle of the "B" range. <S> I provide a menu of extras they can add to earn the remaining points--and even exceed 100%. <S> Often the students and I will collaborate to come up with the menu of extras. <S> For example, a recent assignment involved asking the user for a ZIP/Postal code, fetching the current weather conditions from an online weather service, and then displaying the temperature, city name, and wind speed. <S> Extras included: Toggle units between metric and imperial. <S> Kelvin, too, if they wish. <S> Must use methods to do the conversion. <S> Display wind speed in smoots per day. <S> Again, use a method to do the conversion. <S> Display an icon showing the current conditions. <S> Learn how to map conditions onto an icon filename. <S> Display the forecast for the next few days. <S> Use an array to hold the data. <S> Change the fonts, background color, button appearance. <S> etc.. <S> All the extras have to be documented <S> so I (the grader) know what features to look for. <S> I haven't had any pushback from the students. <S> Sometimes life gets in the way and they only have time to complete the minimal assignment. <S> But everyone has an opportunity to earn the extra points because many of the extras are really easy to implement. <S> Providing students some extras to implement gives them more creative control over their projects. <S> I can't begin to count the number of times other students got excited over seeing what others did. <S> "How did you get the background color to change based on the temperature?" <S> "How did you get it to look up your location automatically? <S> " It gets them talking to each other and, inevitably, learning takes place. <S> I think this is where some students get upset; they don't want to be responsible for their own grade. <S> Be up-front with them: <S> tell them they get to decide what their grade will be. <S> Tell them this gives them an opportunity to complete the assignment even if they can't do all of it. <S> Tell them an "A" on an assignment is reserved for students who go above and beyond the minimal requirements. <S> Then make it relatively easy to go "above and beyond." <A> Ooh, I have experience with this one! <S> I tried once giving a huge lab with lower scores for progressively simplified versions (to allow for students with lower abilities to still complete the lab), and it backfired tremendously. <S> There was a lot of anger, and students did far worse than they should have by opting into inappropriately high versions. <S> It was a consistent phenomenon, and matches up with the psychological understanding that we are more afraid to <S> lose than we are happy about gaining . <S> And thinking about it now, their anger makes total sense. <S> We should grade a student on their work, here and now, in our class. <S> The fact that other people exist who find that work simple should not mean that high grades are intrinsically out of reach. <S> We are penalizing people not for their efforts in the class, but for the existence of other people. <S> That was several years ago. <S> Since then, I have used tiered assignments many more times, but under a different scheme: I award a laughably small amount of extra credit for the harder version (typically 2 to 3 points out of 100), and still allow for a grade of 100 on the low version. <S> After all, the higher version only exists to make sure I am not wasting the time of the more advanced students. <S> There are always students who take the harder versions under this scheme. <S> Many students are motivated to learn, and don't want to do assignments without any challenge to them at all. <S> The small reward is simply a token of encouragement to assure the student that you really do want them to try and stretch themselves, and that is really often enough. <A> At least give it a bonus. <S> In the “real world,” things get more “rewarded” if they are more user-friendly. <S> More people use things that have lower barriers to entry to use. <S> I’m just a student <S> and I have TA’d once, but <S> all my classes that have offered doing harder things (Hopcroft minimization on a partially built NFA and DFA graph generator, for example, or using user input on an assembly language assignment) have offered them for bonus points.
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For one assignment I gave the students a choice, either a simple one or a rather harder one. Tiering assignments puts the score they receive squarely on their shoulders.
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How do you wow second-year students into saying "bare-metal programming is cool!"? Next semester I will be TAing a computer organization/assembly language course. I will be full-fledgedly (co-)teaching the lab. The first lab will take place before the first lecture, so me and the other TA will partly be responsible for preparing the students to not resent this class they're forced to take. At this point, the students have taken an intro class with Python and a class on OO concepts in Java, and they might be taking a language-agnostic algorithms class at the same time. The professor's standard way of motivating the concept on the first day is showing how going through an array column by column is slower than row by row even though they give the same result using the same approach. Therefore, I have to motivate on two fronts: why is assembly programming (or even C) interesting/relevant, and why is computer organization interesting/relevant. The latter may seem obvious if you're already in the know, but it sure didn't for me before I took this very course. Here are some of the points that I already intend to include in my opening spiel (everything that starts with a backslash is spurious): "If you go into data science: the information in this course will explain why certain programs are slow, which is important if you're churning a lot of data. \You will learn how to write faster programs in general. You will understand how computers actually work, no magic [I don't have to mention that they won't learn everything]. \This class might make you interested in systems-level programming, even considering a career. Do you ever feel awed at those other guys with their cool Arduino or Raspberry Pi projects? This class will teach you how to do what they do." What are some other motivators that I can include? EDIT: Just to be clear: I have no control over the lab, and definitely none over the lecture. I won't even be present for the professor's lecture. What I have control over is what I explain as I explain the pre-baked labs, which in the first three weeks include an introduction to ssh, C, certain binary algorithms, and pointers. Aside from the ssh, these are supposed to segue everyone into asm. <Q> First, just a disambiguation: are you teaching Assembly language or C? <S> Cos, they are not same as your question seems to suggest. <S> C is a high-level procedural clean code language with tremendous abilities to speak to the bare metal similar to but not as Assembler pls. <S> It may help you bridge to assembly <S> but it is not assembly. <S> Let that be clear to your students. <S> Never taught machine programming/ASM. <S> But your question touches something in me: the need to wow! <S> the student; I have same predilection with students. <S> So I felt obliged & did some talking with friends in the know and some research. <S> Here’s the widow’s mite I pieced together. <S> Hope it helps:You can add the following to your first lab “sales pitch’: <S> Let the first lab be a NO CODE, no Technical stuff class. <S> Just getting familiar with selves and ASM in a general way with nothing too technical and thus “intimidating” or “off-putting”. <S> The class should be (pardon my cliché): sugar and spice and all things nice. <S> Toward this: Add to your spiel, a history of Assembly telling them of Kathleen Booth & others etc. <S> Make it interesting. <S> Search & find some spectacular successes and exploits using ASM and also some disasters of sloppy ASM. <S> Apart from sparking interest and discussion, the last part will have the additional pedagogic value of sensitising the students to their power as oracles speaking to the small dumb “god” in the machine. <S> Also it will put them on notice of the enormous responsibilities their heightened power as bare metal oracles imposes on them to avoid sloppy code (not only for ASM but programming generally). <S> Let the students see how the higher level languages with their swagger and leaky algorithms are actually, mostly dependent on ASM and C. <S> Let them see that a lot of our higher level constructs e.g. macro were borrowed from Assembler. <S> As @Buffy I. rightly pointed out, talk alone can’t win a non-committal or skeptical mind. <S> To give them something interesting: show them some good things (e.g. games) made in Assembler and display for them on slide (s) <S> the assembly code snippets that made such things. <S> In this regard I found some of these online and hope they may help or stimulate some interesting ideas: <S> https://spectrum.ieee.org/geek-life/reviews/three-computer-games-that-make-assembly-language-fun.amp.html <S> https://www.quora.com/What-are-some-cool-assembly-language-projects-I-can-do?top_ans=21546329 <S> https://brianslam.wordpress.com/2014/04/06/assembly-is-fun-sort-of/ <S> https://news.ycombinator.com/item?id=16710543 <S> This one is a Compendium of Assembly Coding Practices from Coding Project. <S> It may help illuminate your teaching: https://www.codeproject.com/Articles/1116188/40-Basic-Practices-in-Assembly-Language-Programmin <A> You may not win if you just use words. <S> One of the most fun exercises I ever did was to produce a Quine in assembly language. <S> But, instead of producing a textual version of itself, as most Quines do, it produces a running copy in memory and then executes (branches to) that copy. <S> The copy seems to act as if the program is moving through memory. <S> As such, the program is called an Animal. <S> This was once a standard exercise at Dartmouth, and I learned it from faculty and students there. <S> A more elaborate version will erase the old copy as it creates the new. <S> The book XINU (XINU Is Not Unix) by Douglas Comer <S> has some interesting things. <S> One of which is a microkernel for an OS. <S> Unfortunately, this is also one of the skills needed by machine level hackers. <S> To run such a program you need to assure that the OS won't get in your way, however, so you might need to do this on a simulator. <S> You can also do interesting things with race conditions and such that are harder to teach in higher level languages. <A> Forth is very interesting language which can run on bare metal, and also be as high level as you want (I've see a compiler/interpreter of subset of Pascal implemented in 11 pages) and will stretch brain of your students. <S> I know it did mine :-) <S> And is trivial to code some definitions in Assembly if you want. <S> Code is incredibly compact, ideal (and still used) for embedded systems. <A> I would argue the best way to do this is have some demonstrations prepared: <S> things they can build with the tools you're teaching that "look" flashy and exciting. <S> before you give them the tools to build it or things like it.
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Show some cool programs written in C, demonstrate some sort of Arduino-based program that looks interesting (a relatively simple one I've seen waters plants), something in assembly that looks interesting, and so forth. Instead, give them interesting but challenging exercises to do. Make them say, "I want to build that!"
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Is less than comparison more natural than greater than comparison? I was teach on mathematics that on real line small numbers are on left and big numbers are on right. Therefore, I think the comparison 0<1 is more natural than 1>0, and in general, x less than y is easier to read than y greater than x. Is there any statistics if there are less bugs on programs that uses only less than comparisons than programs uses greater than comparisons or both? <Q> I think the typical order has more to do with grammatical conventions actually. <S> Joe is heavier than Bob Joe is the subject, the one we're talking about; Bob is just an object we compare against. <S> Joe weighs more than 90kg vs. <S> 90kg is less than Joe weighs <S> The second one is a very odd sentence. <S> [subject] [verb] [object] [variable] [operator] <S> [constant] This would be a pretty normal construction, such as: x < 0 or x > 0 <S> but odd would be: <S> 0 < x Because the value of 0 isn't changing. <S> Zero is not the "subject" of what we're doing. <S> x <S> is the subject, the variable, the interesting thing. <S> So what if we're comparing two variables? <S> x <S> < y <S> It's possible both of these are new values to us, but intuitively, this code feels like it's more about <S> x <S> than about y . <S> Consider: <S> if x < y: do somethingif x <S> > z: do something <S> Now, clearly, x is our main subject, running against various other variables to see if something needs to be done. <S> So, my impression is that any preference for < over > or otherwise pales in comparison for the preference to put the "subject" of the comparison on the left. <A> You could, perhaps, create an instrument (as in a compiler) to look for such things and look for effects in, say, unit tests of the code. <S> But that implies that a lot of things come together. <S> But, I would also suggest that your basic understanding of human psychology may be naive. <S> It could well be that there are people who actually think more effectively in "greater than" mode. <S> As a mathematician, I've often been confused by left-right and by east-west, especially when they all show up in the same context. <S> But it is, I'm pretty sure, because, I look at things with a "frameless" view. <S> What is left and what is right depends on where I think of myself as viewing from. <S> Also, some times it is just more "natural" to express things with greater than, as in "error > 0.05". <S> So, I think a teaching "rubric" that punished students for using one form over the other would be misplaced. <S> It would, in some situations, lead the user to perform an extra step in their thinking, and that, alone, could lead to an error. <A> Similar to Buffy, I suspect that which use is more natural depends on the framing of the problem. <S> while (countdown > 0) makes perfect sense. <S> By contrast, while (0 < countdown) feels less intuitive, if only because there is a bias towards leaving the variable on the left side of an expression. <S> I think that the key (and this is what I would communicate to my students) <S> is to make whatever choices you make carefully reflect the mental model of the problem. <S> This should create the clearest code, and produce the fewest errors.
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First, I doubt that there are any such statistics because the effect would seem to be so small as to be overwhelmed by other, more common, things.
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How to prevent organization/OS students from becoming premature optimizers? While I'm sure that the comp-sci 101 mistake of having a triple nested loop with two recursive calls is sure to be cured by a decent comp-org class, it can have the unintended side-effect of turning students, enlightened by this hidden knowledge of registers and memory management, become obsessive about unrolling loops in trivial ways and trying to out-O3 the compiler like it's ($CURRENT_YEAR - 40). What is the prevention to this error of learning in the course of teaching the subject? I doubt that most students will ever be in a situation where there will be a difference caused by writing something like struct baz{char a; int z; char b;}; . <Q> I'm honestly not that I would address this problem at all within my own courses, but if it is to be faced, I suspect that the solution would be something like this: <S> Immerse students in their current layer. <S> Really teach the metaphor and thought-process of the layer that they are currently in, and only accept code that utilizes that model of thinking. <S> Tell students to address their efforts here. <A> The way that everyone generally learns this lesson is to spend a significant amount of time tracking down an efficiency issue that is nowhere near where you expected it to be. <S> I'm not sure there's another way to really learn the lesson. <S> As an example, here's an exercise which illustrates the problem: <S> Write an implementation of an open-addressing hash table set. <S> The keys are 64-bit integers. <S> There are two operations: initialise, and "add an element if it doesn't exist, return a boolean which says if it was already there". <S> Use a prime-sized table, and make sure it grows if it gets too full <S> (e.g. require that it start modest-size and grows if the length of a collision chain is greater than some constant). <S> The hash function should be specified to eliminate that as a variable, but of course students are free to implement it however they like. <S> The exercise is to write it and test it for correctness as well as you can, doing all the optimisations that you can think of, do all the timings you want, but don't actually profile it yet. <S> Give your best guess as to where the biggest remaining bottleneck is. <S> Now use instruction-level profiling to find out where it actually is. <A> It might be helpful to use a tool such as Compiler Explorer . <S> It allows one to put side by side C code and its compiled version. <S> It can be used to show that the compiler often generates the same assembly code for the "naive" code and <S> the hand "optimized" one. <S> It also supports compiler flags, so you could use it to show the difference between unoptimized code and -O3 .
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Warn students about the dangers of premature optimizing Show students how to use a profiler in order to figure out what is actually slowing their code down.
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Learning suggestions for AI and neural networks for a mathematician I am a mathematician who has done programming in Python, Java, and R. I would like to learn to make neural networks and artificial intelligence. Are there any good books for self learning AI for a person like me who loves learning theory behind neural networks, and who can learn by proving theorems and thinking the theory behind AI? When I just read Tensorflow's or Keras's documentation, I found that I couldn't understand how the networks work. <Q> The online textbook Neural Networks and Deep Learning by Michael Nielsen is quite good for mathematical content. <S> It assumes the reader understands calculus, but requires no prior knowledge of machine learning. <S> The book's own introduction explains fairly well what the book is about: <S> The purpose of this book is to help you master the core concepts of neural networks, including modern techniques for deep learning. ... <S> One conviction underlying the book is that it's better to obtain a solid understanding of the core principles of neural networks and deep learning, rather than a hazy understanding of a long laundry list of ideas. <S> If you've understood the core ideas well, you can rapidly understand other new material. <A> Higham and Higham's Deep Learning: <S> An Introduction for AppliedMathematicians is a fairly short introduction to neural networks that is written with mathematicians in mind. <S> Another reference I would recommend is Shalev-Shwartz and Ben-David's Understanding Machine Learning: From Theory to Algorithms , particularly chapter 20. <S> Both of the above approach neural network theory in the more traditional Definition–Theorem–Proof structure. <S> I think it is worthwhile to build a simple network yourself in order to learn the principles before diving into a framework such as TensorFlow, if you're hoping to gain understanding of the principles rather than treating a neural network as a black box which might work, or not. <S> For some theoretical background you may also find interest in Hornik et al. <S> (1989) and Rumelhart et al. <S> (1986) <S> if you have access. <A> @kaya3's comment links an excellent e-book, which describes the math in fair detail. <S> I'll never get tired of recommending 3blue1brown's amazing video series that both motivates the problem and gives basic intuition but doesn't shortchange the math: https://www.3blue1brown.com/neural-networks
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The recommendation of Neural Networks and Deep Learning in kaya3's answer is useful for this, as Nielsen does write neural networks from scratch to demonstrate.
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Debugging a submission that works well on student's computer but not on my computer I teach a course in C++. Often, students submit a homework assignment that works well in their computer (they send me a screenshot showing that it compiles and runs perfectly), but when I run the assignment on my computer, I get a "segmentation fault". This is, most probably, due to some pointer-related bug or an uninitialized variable, that results in an "undefined behavior": in the students' computer this "undefined behavior" happens to work fine, but it is still an error. When I tell this to the students, they do not know how to work towards solving the problem, since they cannot even see it on their computer. There are 160 students (with 2 instructors and 3 TAs) in the course, and I do not have time to debug their submissions on my computer, or to give them my computer for debugging. One solution is to have a shared server, and have all students submit their exercises in the same server, so that everyone - including me - work in exactly the same environment. However, currently I do not have such a server so students work on their own computers, which can be Windows, Linux or Mac. Additionally, having an identical environment for everyone is not a complete solution, since it is still possible that a submission happens to work well on this identical environment, despite it having an "undefined behaviour" bug. An identical environment thus only guarantees that, if the students do not see an error, then I will not see it too. How can I help students debug their code in this situation? EDIT: A related problem is that, when the students submit such a solution and I tell them they have a bug, they say "the bug is in your computer! See, my code works well on my computer!". So a related question is: how can I explain to them that there is a bug in their code, even when they do not see it? <Q> You've said that having an identical environment for everyone would be an incomplete solution, since students' code could still work "by accident" in that environment. <S> One option would be to provide access to two or more sufficiently different environments which would be the same for everyone; such environments could be provided in several ways, for example: <S> Distribute virtual machine images, with instructions for how students can use them to test their code. <S> Provide access to virtual machines through a paid service; for example, Codio is specifically designed for use in CS education. <S> There are some web services such as repl.it , which compile and run your code, and show the results in a console. <S> Some universities have student-run computing societies offering accounts for students on a shared server. <S> Different environments may already be available if students are on campus, and the campus has enough different computer labs open for student use at some times. <S> Assuming you have a script that can automatically run all submissions, it shouldn't be a lot of extra work to run that script twice. <S> Another option is to provide students with a software tool which can detect and report undefined behaviour, as discussed in this Q&A on Stack Overflow . <S> Such a tool could also be used to give feedback to students whose submissions fail on your machine during grading; although static analysis and other techniques won't generally be able to detect <S> all kinds of undefined behaviour, the kinds they do detect should cover most or all of the mistakes that students are likely to make. <A> Your student/staff ratio is pretty unfavorable. <S> This makes everything difficult. <S> If you had a few more TAs or could find the schedule time, I'd make one of the TAs the person to handle all such technical issues. <S> It would need to be the one with the highest "geek cred" I think. <S> But debugging stuff shouldn't be the instructor's job. <S> Part of the job of the super geek TA would be to figure out why such things happen and to feed it back to the instructors so that such things can be avoided in the future. <S> The symptoms you exhibit might be as simple as the fact that student machines probably have different memory configurations and so bounds errors might get caught on one, but not another. <S> And if they have different OS's and different versions of C++ then there are lots of places for failure. <S> But with over a hundred students, your time isn't well spent debugging the code of individuals. <S> Appeal to the administration for adequate support. <S> Offload such things to that support staff. <S> Your top geek might also be able to schedule a periodic "debugging lab" for students. <A> You could encourage them to use tools like compiler warnings and valgrind to try to check for bugs. <A> As early as possible in the course, and again when appropriate examples arise, you should "round up the usual suspects." <S> (It's a Dick Tracy reference, but that does not really help.) <S> You could include this as a "sidebar" feature of many classes. <S> And you could have a "crib sheet" listing the most common such mistakes. <S> For example one frequent mistake is the "wild pointer. <S> " You allocate memory using "new" and have a pointer point at it. <S> Then you later delete this memory through the pointer. <S> Then still later you reference the same memory through the pointer. <S> Your program no longer owns that memory, it's a protection fault. <S> There are several common variations on this, and it can be very hard to debug. <S> This is just one example. <S> There are a bunch of these. <S> If you make them aware of these early in the class then hopefully you will get them learning how to code well, not just vigorously. <S> In C++ there are a number of idioms that seriously reduce wild pointers. <S> You could dedicate part of one class to debugging an example of this kind of error. <S> It would probably save you a lot of time marking assignments. <S> Or if they have tutorial time, that could be a task you drop on your tutors. <S> You could get them into the following books to look for more, and other related issues. <S> These are the books I wish I had when I was learning C++. <S> https://www.amazon.com/Exceptional-Engineering-Programming-Problems-Solutions/dp/0201615622/ <S> https://www.amazon.com/Accelerated-C-Practical-Programming-Example/dp/020170353X/ https://www.amazon.com/Code-Complete-Practical-Handbook-Construction/dp/0735619670/ <A> Is this using different versions of gcc ? <S> Have the students compile with full warnings and with different level of optimizations. <S> I wonder: could the emitted warnings be of a kind that the compiler will only warn about at a certain optimization level? <S> Either way: making the students see the effects of this type of side-effect is very valuable in itself. <S> Now, how to ensure that they deduce the issues, that would be interesting and valuable.
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To catch undefined behaviour when grading submissions, you could test their code in the same two (or more) environments that students have been encouraged to use.
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What evaluation methods can be used that don't involve testing but are adaptable to online courses The current situation with the spread of a serious disease worldwide has caused a number of universities and schools to move courses to an online model where students don't meet face to face in large groups. The problem of evaluating students then arises, and traditional tests are ill suited for an online model as it is much harder to monitor them or assure validity. Ideally, any evaluation method should foster learning, not just memorization, so traditional testing has its own downside. Perhaps the current emergency can result in finding better evaluation methods that are also amenable to use online, as well as in traditional classrooms. Have you used innovative evaluation methods - beyond testing - that foster good learning and proper student habits but which can be adapted to courses that don't meet face to face for instruction or testing? Can you describe what you do. My own preference has long been to replace traditional tests in ordinary classrooms, and especially high risk, anxiety inducing, tests with small group and pair projects. This was combined with peer evaluation. In the current situation, it might be acceptable for students to meet in pairs or small groups with less risk than meeting in larger groups. But, it would probably have to be done in a way that meeting face to face is optional. <Q> The problem in their own words, How their algorithm works (with code), and How they tested it. <S> Students had a few weeks to complete this task, worked in their own time, and then submitted their report to the university's Moodle site; so this kind of assessment could work equally well in a non-face-to-face course. <S> The idea behind asking students to explain their algorithm came from the fact that interviewees for software jobs often have to solve a problem during the interview and explain how their solution works. <S> Being able to explain how one's code works is also important for many other things a programmer might do, like rubber-duck debugging, code review, or writing good answers on Stack Overflow. <S> Your question doesn't dwell on it, but one of the key differences between in-person and online assessments is the opportunity for cheating and the difficulty of detecting it. <S> As a convenient side-effect of having students explain the problem and their solution in their own words, suspected cheaters can be identified in two ways: A student who is unable to write the code themselves is usually also unable to adequately explain how the code works. <S> A student who also copies the explanation (or parts of it) can be detected by standard tools such as TurnItIn, so you don't need a more sophisticated tool for comparing code similarity. <S> In the former case, a poor explanation deserves a low grade anyway, whether or not they cheated. <S> In the latter case, my experience of running the assessment over two years with ~250 students each year is that TurnItIn works well enough for catching students who copy from an online source or from each other. <S> With fewer students, you can group the assessment submissions by which problem they attempted, and probably notice any collusion yourself even without a tool like TurnItIn. <A> I agree with kaya3. <S> You can assign open-ended projects where students apply techniques from the course. <S> Or you can give them more structured projects, e.g., from this book by Havill <S> (the website includes skeleton code): <S> http://discovercs.denison.edu/ or inspired by these data science projects by Nolan and Temple Lang: http://rdatasciencecases.org/Data.html <S> You could build up to the projects with more and more complex problem-solving done in an online system, where the grading is automatic, like CodingBat. <S> Students can go to Preferences and "Share To" so that their instructor can see a report on their progress. <S> You could assign them 4-5 problems a week, and a project after a couple of weeks of building up their problem solving ability. <S> A zillion exercises in Python can be found on my various pages on there: https://codingbat.com/home/david.white@denison.edu/ <A> If your main concern is related to cheating in tests, there are some ways to somehow minimize it (not 100%, though). <S> I am in "forced" quarantine since March 4th, so, <S> almost all the 2nd semester is held online <S> (I haven't returned to the uni since, so haven't the students). <S> :) <S> I and all the CS teachers at my Uni rely mostly on small quizzes, oral presentations, small assignments or larger individual ou group projects. <S> Traditional tests will still take place, but their weight in the final grade was reduced. <S> In any case, it is almost always assumed that the tests are open-book tests, so the students are asked to give their opinion or apply some concepts and not simply give definitions. <A> One excellent resource to introduce students to Python programming remotely is CMU CS Academy (with which I am affiliated). <S> CMU CS Academy is a free online, interactive high school computer science curriculum. <S> The curriculum includes notes, exercises with an autograder, creative tasks at the end of each unit to apply what they have learned so far, as well as quizzes. <S> They are currently providing daily webinars for educators interested in learning more. <S> You can sign up at https://academy.cs.cmu.edu/r/12103?fbclid=IwAR0b7O9En6dRqFp6p8a2cik62GAXlHyiWqnXK3oELM3afHReZQf-lrakBrk
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As part of an algorithms module (first-year undergraduate level), I got students to choose a computational problem from a list of options I provided, write an algorithm to solve it, and write a 750-word report explaining:
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Detailed lecture series for automata theory or theory of computation I need a detailed automata theory (or Theory of Computation) video lecture series to go hand in hand with the classic text books mentioned in this question The books are fine but I am having problem in understanding many portions of the texts on my own. I want to develop an intuition about the theory and related problems which I feel I am quite lacking. (I am following "Introduction to Automata Theory, Languages, and Computation" by Hopcroft, Ullman, Motwani) <Q> In the course I co-teach <S> on Automata, Computability and Complexity Theory <S> we use the excellent videos by Harry Porter to replace our classical lectures, and use our contact hours instead to practice with the material together with the students. <S> Porter follows the book "Introduction to the Theory of Computation" by Sipser. <A> A quick google search reveals two courses on the MIT OCW website: Automata, Computability, and Complexity taught by Scott Aaronson; has Sipser along with two other texts as recommended reading, and comes with lecture notes and assignments <S> Theory of Computation taught by Sipser himself (!) <S> with the 2nd edition of his textbook as required reading. <S> It comes with assignments, exams, and notes on what readings should be done for each section, but does not have lecture notes uploaded. <S> If neither of these suit, there is a whole category on the MIT OCW website that has computational theory course materials. <S> If you want video lectures, there is this series on YouTube taught by a UC Davis professor based upon Sipser's textbook (the series is 26 lectures, each about 1hr15 in length). <S> Most of these are based on Sipser, not Hopcroft et al., but Sipser is another classic text recommended in the question you link, so I figure these will likely work for you. <S> Good luck! <A>
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I high recommend taking a look at the Stanford CS103 course page archive , which has links to very engaging lectures, and lot of great supplementary resources, such as handouts, problem sets, and lecture notes / slides.
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How can I find someone online to mentor me on my first research paper? I am an undergraduate student, and I have an idea which I want to explore and write a research paper on. But I am totally new to this.I don't have good CS community at my place. So I can only look for a distant mentor.Please tell me how and where (sites, forums) it is possible. <Q> If the semester is in session, you can go to their office hours; otherwise, you can email your advisor or another professor who knows you. <S> Even if it's outside their area, they should be able to steer you in the right direction. <A> Depending on how serious you are (and what you mean by the word "research") <S> your best bet may well be to search out professors in that area of research, no matter where they are in the world. <S> You could simply explain your position to them, and ask for they would be willing to work with you on the paper. <S> You may well get some "yes" answers. <S> This could also be a good way to start a relationship that could lead to a doctorate. <S> Good luck! <A> Answering your questions with suitable answersfor doing research you must have the following:- A topic or brief subject on which you want to work. <S> In CS field, start find faults and raising questions to yourself about the topic you learn, e.g. while learning sorting in Data structure, what other technique you can suggest while simplifying existing techniques, etc. <S> After the topic is decided, find who had done what work on your topic. <S> It means to find references to your research work, because without references you cannot write research paper. <S> e.g. search websites of IEEE or research gate. <S> otherwise you will remain just a blogger. <S> hahaha Al <S> last but not the least, find a research guide online or offline. <S> For any other queries, you can post me again
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I would suggest taking to professors at your institution. Read any book on research methodology
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How useful it is for math student to learn programming to find proofs or counterexamples? I study mathematics and sometimes I have difficulties to find proofs or counterexamples to some problems. Is it useful to learn programming to find counterexamples or proofs? How useful it is for mathematician to learn for example Coq or Lean? <Q> This is pretty much in the realm of opinion, but as a math PhD and a long time CS professor, I'd guess the answer is no. <S> Programming is fun and programming can be useful, but its application to proving theorems in mathematics is very specialized and a bit limited. <S> And it generally doesn't apply to the sorts of things a struggling math student wants to learn. <S> There are a couple of exceptions in which programming was instrumental in establishing a proof. <S> One is the Four Color Theorem which was originally proved with a computer because of the huge number of different possible planar maps. <S> But mathematicians, like myself, find that proof unsatisfying and would prefer one that was more analytical and which would lead to more insight. <S> But these sorts of cases are very rare. <S> But, theorem proving, like anything else is a skill best learned through practice. <S> Once you have tried and eventually succeeded at proving some theorems, perhaps after false starts, you will start to gain insight. <S> Every success can lead to the next success. <S> But it is hard work. <S> And the work may not get easier as you go, since you will probably take on harder problems. <S> But practice, practice, practice. <S> Programming does, however, give you some practice with thinking logically and breaking a hard problem down into smaller, easier, parts. <S> In that sense programming can be a bit helpful. <S> But to learn math, just do math. <S> On the other hand, there are automated Theorem Provers <S> that can do some interesting things. <S> But their results don't generally lead to the insight into a problem that a mathematician needs and to build one of them requires deep insight to start with. <A> The only thing that programming can do for you is teach you logical thinking, if you have problems there. <S> The computer won't let you use assumptions or take shortcuts. <S> You have to create a complete, logical sequence of instructions to get from the problem to the solution. <S> And that skill is of course also needed for mathematical proofs. <A> Programming is very useful in the process of conjecturing, and to some extent even in proofs. <S> Here are some examples from my own research, in theoretical computer science and combinatorics: <S> An algorithm for maximum coverage (a basic combinatorial optimization problem) employs a non-standard objective function, with finely tuned parameters. <S> These parameters were obtained by solving a linear problem on a computer. <S> The parameters depend on $n$ , so I solved the linear programs corresponding to small $n$ , and generalized the solution. <S> The solver also found the tight constraints, and this was very instrumental in the proof. <S> The construction of the Gelfand– <S> Tsetlin basis for the Johnson scheme (equivalently, a canonical eigenvector basis for the Johnson and Kneser graphs) came out of some experimentation in a computer algebra system; I don't know whether you consider this programming. <S> Several papers in social choice theory aimed at proving phenomena which were first observed experimentally; this required programming in an efficient language. <S> Optimal gadgets in a paper in circuit complexity were found by exhaustive search using an efficient computer program.
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I would say that programming is a useful skill, at least in certain areas of mathematics.
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Creating a pre-recorded lecture I have created a PowerPoint presentation and I want to create a video of me presenting it. I'm looking for a software to make my life easier. The features I'm looking for are: Can record a 25-minute video for free. Works on Mac. Can record the screen and me (audio+video). Lets me rewind while recording and continue from there, so that if I make a tiny mistake I can just go a few seconds (or one slide) back and continue recording. Any suggestions would be greatly appreciated. <Q> It is not the easiest program to use, but you can find plenty of tutorials on YouTube. <S> While rewinding the recording again might seem appealing, it is very common to find out more errors after you complete the recording. <S> In that case, you need a better video editor. <S> OBS studio might be enough, but shotcut is your best bet. <A> For high-stakes presentations, I suggest writing a script. <S> 1 page of well-spaced A4 reads back at ~3 minutes and allows you to get your points across clearly and concisely, especially points that need to be well-phrased. <S> This should enable you to do a one-take presentation on Zoom or OBS. <S> If you baulk at writing a presentation, record yourself, transcribe it <S> (I think that’s built into Word on a Mac) then tidy it up. <S> If you are like me, that will involve deleting many instances of the word “arm”. <A> If you don't mind skipping your own face, your easiest, cheapest option is probably PowerPoint itself. <S> PowerPoint allows you to record audio (and animations) for each slide, set up timing for the next slide to start automatically, and export the entire thing as a video. <S> I'm not aware of any product that both fits criteria 1 (free) and criteria 3 ( video of you). <A> If we look at the world of movies. <S> We see that long single takes (cut less scenes) are rear and often talked about. <S> There are hard to do, and slow down the pace of a movie. <S> Consider recording in smaller slices. <S> Next consider that mistakes can improve teaching. <S> If you show your students that you also make mistakes, then you can improve their confidence. <S> When I teach the same class over and over, I get good at it. <S> When doing demonstrations, I have to concisely add in mistakes. <S> I am demonstrating how to program. <S> If I show that I get it correct first time, then I am not showing right.
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OBS Studio fills your description.
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Any good resource for introducing kids to programming using Python's Turtle Graphics? I would like to start volunteering with kids and young teengers in my community by introducing them to programming. I thought teaching them the basics of python would be a good start. I have some experience with teaching in general (but not with teaching kids about programming). Are there any resources that could help me or at least inspire me to make a good curriculum that goes over many concepts with turtle? Thank you! <Q> I have found that Python is not the best tool for teaching elementary and middle school students an intro to programming. <S> Turtle is nice, but you run out of things to do pretty quickly. <S> If you move on from Turtle to console based coding, many students find it less engaging. <S> Scratch and similar visual languages are much more engaging for younger learners. <S> You will be surprised how full featured they are. <S> There is a lot of great algorithmic teaching that you can do with these. <S> If you really want a traditional text-based language, you might check out Greenfoot (for Java). <S> But again, younger learners get lost in the symbols pretty quickly, so it would not be my first recommendation. <S> Scratch can be much more intuitive for them. <A> I concur with Bryan R that Turtle might not be a great choice for an in-depth introduction. <S> A quick google search for "python turtle lesson plans" reveals that most plans are for one to three lessons, after which, you have pretty much exhausted what Turtle has to offer. <S> There are various paid resources for Python Turtle at teacherspayteachers . <A> If these kids are true beginners Python is a bit much. <S> Try Scratch or Alice. <S> If you really want a line-code language go for Small Basic. <S> All of these have excellent resources available on their website. <S> Thunkable and App Inventor can also be a good start if you want to try something different.
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If you are open to a slightly different, more graphical, version of Turtle (called "Tina"), there is a whole book of lesson plans available at nclab .
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Grading source code in an online environment In the past students have submitted hardcopy of the programs and output for grading (electronic version was also supplied if I wanted to run the programs). I always annotated and graded the source listing and associated output on the paper copies that I then returned to students in class. Now with COVID-19 and teaching all online, I will only have Canvas submissions, and I am able/willing to print them as needed, but no way to get feedback/hardcopy easily back to students. This is particularly important for my CS I students. What are you all doing with regard to this? Annotating paper is the most time efficient way for me to do this. I had one colleague last spring who took images of all the grading and then uploaded a set of .jpgs for each student - a ridiculously time consuming process that she gave up on soon. Scribbling on source code, circling sections etc is what I'd like to do. Any suggestions? Please note that this is mostly for my CS 1 course - many of these students will not have had any programming experience. They will struggle enough with the basics of Eclipse and Java - so I don't necessarily want to burden them with extra technical demands. <Q> I would suggest you use a code review tool. <S> This is something they will likely need to be using when working in industry. <S> So worth upskill them on it now. <S> You can use githubs one for free.(You are teaching version control so that should be easy enough) <S> Get your students to create a pull request and review that. <S> You can highlite specific lines and put comments against them etc. <A> To me, it seems a little odd as an approach and inefficient. <S> That said, if you wish to have a similar workflow digitally, you might want to consider using a tablet computer with a pen, Microsoft OneNote, and then saving the final output as a PDF. <S> This will allow you to draw, scribble, and write freely on their submitted code. <S> As a side benefit, you'll also be able to put in links, pictures, or other diagrams, assorted and sundry as you find useful. <S> Typically, I provide feedback either in bullet points or side-by-side in person ("in person" in this context <S> means using screen share in Zoom). <A> If you can create PDF files (as you indicated in comments) you can use Adobe Acrobat Reader (the free one) to add comments from a keyboard into the code and save it. <S> This is what I use for most student work, listings, dissertations and so on. <S> You can save it and re-upload to the VLE or whatever feedback mechanism being used. <S> Of course, if you have a tablet device or even a sketching pad attached to a desktop you can add more freehand annotations in the old style. <S> However, I have moved from annotating code for a more test-based development mechanism for giving coding feedback. <S> The students now have to run the test scripts I write and upload the results rather than the code at intermediate stages for formative feedback. <S> I only feedback on the code at the summative stage. <S> I find that, with >250 students, I need to let the computer do more of the work whilst still trying to give some form of helpful information to the students. <S> There are, of course, pricier tools specifically designed for scribbling that others may mention. <S> Another way of doing things is to interact with the students' actual code base and not a listing, using something like Visual Studio Live Code Share. <S> This give feedback at the actual point where they start to deviate from common sense. <S> Some colleagues are doing this technique. <A> Note this answer does assume a batch scanner is available. <S> If you insist on working with printed pages, you could prevent doing (much) manual work returning the files if you either: <S> Keep track of the order of the printed files, correct them, put them in a batch scanner and automatically return the corrected files. <S> Though I could imagine this is not an option due to risk of mixing files due to scanner/printing glitches. <S> Another option could be to print a qr code on the page,print the pages, correct the pages put the corrected papers back into a batch scanner, and process the images using a qr decoder to allocate the files accordingly, this way you are (almost, depending on how good the qr scanner is) certain that the correct corrected papers are returned to the right students. <S> You could also get a notification on the papers that were not scanned correctly since you know how many you printed and hence should scan. <S> If you don't want to be searching for a place to put the qr code in their paper, you could give the students a latex template, or convert their code into a latex template with a qr code belonging to their study number. <S> In my experience pyzbar can be a bit tedious to set up <S> but I found it to practically work identifying qr codes in printed- and scanned pages. <S> Not claiming this is the best solution, I think there would be easier solutions and like DarcyThomas answer better. <A> You can try PDF Viewer Pro by PSPDFKit, saw it in the top list on iOS App Store a few days back, looks like it does what you need. <S> I say iPad because I think it allows you easier to create circles and lines than using a mouse on a notebook.
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It has never occurred to me to use printouts of code, even though I have an older colleague who does this.
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What kind of caulk should I use around my bathtub? I would like to recaulk between the bathtub and the ceramic-tile wall, but there are many kinds of caulking for sale. What kind should I use? <Q> I just caulked my shower last night. <S> I used GE Silicone II caulk from Home Depot. <S> I read up on this a little before picking out what kind I needed. <S> From what I can tell, silicone caulk is good for bathrooms because: It's permanently waterproof <S> It doesn't crack or shrink <A> I just bought a permanent silicone product by GE which is guaranteed to dry in 1 hour and is mold resistant. <S> GE <S> 9.8 oz. <S> White KB Supreme Silicone II Caulk <A> I own a remodeling firm, and this is one of those things that so many get wrong and the manufacturers don't tell you how to get right. <S> There are 3 aspects homeowners never hear:1. <S> All the old caulk HAS to come off. <S> Squeaky <S> clean.2. <S> All surfaces and substrates to be caulked need to be dry. <S> Bone dry.3. <S> Use silicone if you must, but silicone or acrylic, the caulk will need to be redone in 2,3 or 4 years, no longer. <S> It just won't last longer. <S> The dirty secret about silicone is that nothing sticks to cured silicone caulk -- including new silicone caulk. <S> The old silicone has to be completely cleaned off. <S> This usually requires a single-edge razor blade and mineral spirits, followed by an alcohol wipe, followed by a wipe-down with bleach (chlorine or oxygen bleach - the latter being our preference). <S> The last two steps get what the first doesn't; the bleach being very important to kill mold where new caulk is to go. <S> Acrylic caulk, unless it's super hard, is generally much easier to clean-off than silicone. <S> THEN, before re-caulking, the surface needs to be dry. <S> Bone dry. <S> It really should stand for a day without being used before it's caulked. <S> As said, use silicone or acrylic, but assume you're going to be re-doing it in 2-4 years, so, for my nickel, I'd rather save my knuckles and knees and use acrylic caulk than crouch in a tub for an hour plus trying to remove all the silicone. <S> Either way, the tub/shower should not be used for another 24 hours. <S> Do all the above, and you'll have a great finished product -- that will last 2-4 years. <S> Skip a step, and you'll likely find something turning red or black in a matter of days or weeks. <S> A thorough, well-written article -- with step-by-step detail can be found here: http://www.acmehowto.com/home-maintenance/general/caulk-tub-shower.php <S> Wish I had better news, but <S> experience has taught us all the above. <S> Good luck.
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Another factor which may play into your choice of caulk could be whether or not it's paintable, but the most important factor for a bathroom is going to be waterproof/mold proof.
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Are there ways to determine if a wall is load bearing? Other than looking up blue prints, which many homeowners may not have, are there ways to determine if a wall is load bearing? Methods I can think of might include: Going up in the attic to check if ceiling trusses run perpendicular to the wall If the wall is an exterior wall Any others? <Q> Without looking at blueprints, all you can do is make an educated guess. <S> Possible methods include: <S> If it's an exterior wall <S> it's almost always load bearing. <S> If the joists are not continuous over the wall (they are cut short and meet on top of the wall) <S> it is definitely load bearing. <S> If there is a load bearing wall or beam directly above or below this wall, it is likely load bearing. <S> Check the direction of the joists (as you mention). <S> If a joist is running perpendicular to the wall, or happens to fall directly above/below the wall, it can be load bearing. <S> If there's a single top plate, the wall most likely isn't load bearing, unless the wall uses deeper studs than 2x4 (such as 2x6). <S> If it's a solid 2x6 or greater turned vertically going from the jack stud on one side to the other, there's a good chance the wall is load bearing. <S> If there are only cripple studs on a flat 2x4 to give you something to attach the drywall, it likely isn't load bearing. <S> Look for signs that the wall was added after the house was built, newer wood materials, drywall or finished flooring that extend over/under the wall, etc. <S> If the wall was added, then it isn't load bearing. <S> Calculate the span from the known load bearing walls on either side of the wall you are removing <S> , look at the type, size, and spacing of joists above the wall, and calculate if the joists can support the load above the wall without the wall being in place. <S> When removing the wall, cut the studs with a sawzall. <S> If the blade begins to bind in the middle of the stud, then there's load coming down from the ceiling through that wall and there's a good chance it was load bearing. <S> Stop what you were doing and sister a stud to the one you were cutting. <S> If, after you remove the wall, your home collapses, it was load bearing. <A> The methods you describe are probably the best, but if you can actually see the wall, a load bearing wall will generally have a double top plate but <S> a non-load bearing wall usually won't. <A> For many houses, a wall running down the middle of the house, parallel with the roof ridgeline is nearly always load bearing. <S> You also may have easier access to the basement to check joist direction. <A> If it is not, it still does not mean it is not load bearing, but it can help to understand the structure.
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If the joists can't support the load without the wall, then by definition, it's load bearing. If the wall is above a basement or open crawlspace, you can look from below to see if it is on a bean or above a support post. Expose the wall over a doorway or pass-through.
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How do I repair hairline cracks in stucco? The exterior walls on my house which is made of stucco, are starting to get hairline cracks in them. Can anyone suggest a simple, cheap solution for it that doesn't require painting the whole house exterior? <Q> If it were my house <S> I'd get painting! <S> Paint is intended to seal hairline cracks of this kind. <S> Depending on your locality you may find that it's feasible to spray a paint finish over stucco, which can be by far the easiest and cheapest way to do it. <A> It comes in a tube too so you can just attach it to your caulking gun. <S> It needs to be painted over. <S> You need to repair those cracks so water does not get in and DAP will seal it along with a coat of paint. <S> You'll need a plastic spreader to spread the mix. <A> I am fixing cracks right now for an apartment building. <S> There is nothing I am doing that hasn't been done already. <S> Buy some good decent caulk and run a bead over the crack then smear it into the crack with your finger. <S> It will come back slower or faster depending on how well you ran the bead. <S> Good luck. <S> Stucco is cheap junk anyway -- the lattice always rusts and expands no matter what. <A> Kover Krack, textured type from Sherwin Williams <S> just brushes on the paint over.
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I recently used DAP All-Purpose Stucco Patch .
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How do I repair a small leak in a steam radiator? Could this be a big problem? One of my steam radiators has a small leak under the bottom. No hole is visible, but water drips out at a rate of a few drops per minute. Various websites suggest applying a 1 mm thick layer of J-B Weld after sanding and cleaning with acetone. Does the fact that the radiator leaks necessarily mean that it is completely rusted from the inside and that leaks will soon appear elsewhere? Or is it likely that a slow leak is not due to rust, or that the rust is in only one place? The radiator is decades old (perhaps even a century), but has been moved recently in order to repair the floor. The leak is clearly away from the valve. <Q> I haven't had very good luck with repairing steam radiator patches from the outside (sample size: 2). <S> Steam under pressure is very good at finding microscopic holes between patch and substrate, and enlarging them. <S> What I have done successfully is an inside patch with epoxy, using a wire brush and steel wool to prep the surface. <S> Getting at the leak may be a challenge, particularly with a radiator that has more than 4 sections you may need to break the sections apart (if you do, this is an excellent time to get the exterior sandblasted and painted). <S> Simplest and most cost-effective solution is probably to find an architectural salvage shop and replace the radiator (they might take your old radiator as a partial trade). <A> Be sure that the leak is actually in the radiator itself, and not where the valves meet the radiator body: <S> water is very good at travelling a good distance horizontally thanks to surface tension. <S> I check this with a bit of paper towel. <S> If it's not new... <S> then yes, I fear it's rusted. <A> If the radiator has started to go, it may be a futile exercise to plug leaks. <S> Nevertheless, several pointers are: <S> Make sure you know for a fact exactly where the leak is by using flour or talc, eg. <S> Steam is under pressure and can spray into a fine mist through a tiny hole that collects on a surface and runs down. <S> The drop of water might appear far away from where the leak is actually occurring. <S> If corrosion is involved you should clean it out before making the filling, like a dentist. <S> Metal of two different types will expand and contract at different rates. <S> This tends to make metal "patches" of any kind fail after time if the patch materials is not EXACTLY the same as the host material. <S> One trick that can be used in instances where the leak is small and circular is to use a screw. <S> You drill a hole where the leak used to be. <S> Then you tap the hole, ideally with a fine machine thread. <S> Finally, insert a machine screw, perhaps with a single layer of teflon tape. <S> If done right, it will perfectly seal a hole. <S> If the leak is shaped like a fissure, it is very difficult to fix. <S> For a cast iron shell the only real possibility is a thermite weld, but it requires a lot of expertise and experience to do this right, so it is rarely cost justified unless the cast iron thingy is VERY valuable or irreplaceable (not the case here). <A> There are several products made to seal leaks in car radiators. <S> I have seen some amazing results from these, even stopping a "gusher". <S> If the metal has corroded away from the inside, since they are usually metal based, they might even replace lost materials from the deepest spots.
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If the radiator is newly installed it may well be that the hole will sort itself out by filling with mineral deposits; if it's a hot water based system there's also proprietary sealing gunk you can add to the water that'll seal small holes.
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How do I remove wallpaper from drywall? I know there are a lot of different ways to remove wallpaper, ranging from elbow grease to chemicals and steam machines. What way(s) work(s) best? <Q> It depends :) <S> It really depends on how old the wallpaper is, if there are multiple wallpapers glued over each other and how much glue was used. <S> It has the advantage that it loosens the glue without making the wallpaper to fragile to pull it off. <S> I usually try to stay away from chemicals, because they always have some danger for health associated. <A> A mixture of warm water and vinegar works well. <S> or you could substitute fabric softener if the vinegar smell bothers you. <S> Apply a liberal amount with a spray bottle or rag, wait, and peel. <A> I've removed all the wallpaper from our house. <S> In the three bedrooms, it was painted over. <S> I think I've seen the gamut of wallpaper removal. <S> Easy Wallpaper just stripped off in nice sheets. <S> This was in the dining room. <S> It wasn't painted over. <S> It took Maybe 15 minutes to do a 14' x 10' room. <S> Hard <S> This is the technique we used for two of the bedrooms where the wallpaper had been painted over. <S> Messier, much more work, but the only option. <S> Perforate wall paper with wallpaper perforation tool Apply steam using steamer Scrape off paper with 4" putty knife <S> Extreme <S> The last bedroom we did, I came close to giving up and resorting to either tearing out the drywall or some other extreme measure. <S> We tried everything, in the end it took 6 nights of work to do a small (10' <S> x 10') bedroom. <S> The paper was very, very stuck on and then painted over. <S> The steamer could not soften up the underlying glue layer because of the paint, even with very liberal perforation. <S> If you held the steamer on long enough to get the paper off it had already softened up the underlying drywall <S> and you'd very easily gouge the drywall and remove paint/backing. <S> So we resolved to first scraping off the top layer of paint exposing just the wallpaper backing and then using the normal technique for wallpaper removal with just the backing. <S> (I will have to check my notes, as I don't think this is quite the exact steps yet.) <S> Perforate wall paper with wallpaper perforation tool <S> Use a sharp scraper (we found this one worked best ) to remove the top layer of paint. <S> Working one 3' x 3' section at a time, apply steam, scrape off using paper scraper <A> (Ugh!) <S> It can definitely help to rough the surface of the paper before steaming, especially if it's been painted. <S> If it's a real mess then it is actually feasible to plaster over paper, but I'd personally not recommend that approach unless you know a good plasterer or can do it yourself easily. <A> I've found you don't need a steamer or special chemicals. <S> If you do use a steamer, be really careful not to damage the wall. <S> Plaster will break apart, for example. <S> Instead, I've used one of those wallpaper scoring tools to cut small holes in the surface. <S> Then, apply hot water from a spray bottle liberally over the paper and let sit for 30 minutes or so. <S> It should then start peeling away easily with a scraper. <S> Of course this depends on the type of glue used. <S> If this doesn't cut it, you may need to mix some kind of glue solvent in the sprayer. <S> This process worked on a circa 1950's house on plaster walls. <A> My wife and I just renovated a house that had 5 layers of wallpaper in the living room (including the "Hay" wallpaper from circa 1985) and we bought two steamers and went to town. <S> It was the best solution we found. <S> You don't have to spend a lot, just get the inexpensive plastic steamer unless you plan on doing it for a living. <S> She did re-use the steamers several more times for her painting business <S> and they still work well. <S> Matt <A> Fill a plant sprayer with hot water and dishwashing detergent and spray the wallpaper several times and let is soak for 30 minutes. <S> Once the mixture has been incorporated well use a filling knife to remove the wall paper. <S> Repeat this process for wall paper pieces that stubbornly stick to the wall several times in order to remove it. <S> Note: this solution is applicable for removing wall paper from a plasterboard as well.
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If the wallpaper is not too old, and was put on in a proper way, usually, a steamer works very well. A steamer is by far the best option: I've had great success even with multiple layers of woodchip.
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How can I fill a void in a concrete seawall? My concrete seawall (on a freshwater lake) has a void in a bottom corner. It seems to have been created with the void -- it's not a result of trapped water freezing and pushing out a chunk. I'd like to fill the void to avoid future possible erosion. Multiple questions: Should I fill it while it's warm and underwater (summer/fall), or dry but cold (winter)? What should I fill it with? <Q> I believe there are cement products that will cure in water, however I would wait until the winter. <S> Cold is not a problem here, except for your fingers. <S> And you can always find a day in the middle of winter when the temperature is quite moderate. <S> Find a high strength patch filler. <S> Make sure that it attaches solidly to the existing hole. <S> If possible, I would drill some holes into the sides of this hole, then put some non-rusting (brass, aluminum, etc.) <S> bar stock into the hole so that it sticks out into the void area. <S> The idea is to put a set of fingers into the cement patch area to prevent this patch from popping out. <A> Almost all cementitious products cure better, stronger and harder with a steady presence of [fresh] water. <S> As far as placing the product, whichever you choose, in the presence of water, that will depend on specifics that you have not listed. <S> I will say that when large construction companies are pouring underwater footings, say for bridges, they will have the form in place and filled with a heavier than water gel that gets displaced by the concrete as it is poured in/injected. <S> If it is saltwater you can use additives suited to saltwater. <S> Your local concrete store will be able to direct you in the right direction as far as additives go. <S> Be careful about what kind of reinforcement you use - many types of reinforcement are very susceptible to sulfates in the water and will cause spalling if placed too close to the outer edge of the concrete. <S> With regard to your initial description, I would say that most concrete pours end up with a void. <S> As long as no water is penetrating through the void in your wall you likely have no concerns in re.: <S> future erosion. <S> Even if water were coming through this void the concrete has likely formed a crystalline structure that is resistant to "erosion," however if water is coming through then there are many cementitious products available for purchase that will solve this problem. <S> I've used Xypex and at least one other for weeping foundation walls. <S> Best of luck in your endeavor, even if I'm not sure what said endeavor is... Paul <A> Note: What I actually did: <S> Found a relatively warm winter day (the water line was below the void in wintertime), troweled in cement, built a form around the void (it was a corner <S> so I was able to stake the form next to the void while leaving enough space to top off the cement and then push the form right up flush to the void). <S> I went with a bonding cement because the space was deep but not so high and I thought that using stone would prevent me from packing it in tightly. <S> I could have done this submerged, it just would have been a lot colder and wetter.
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If the water is intermittent or tidal you can use a simple fast setting concrete, or a normal concrete with an accelerant additive. Insofar as patching the void is concerned I've had good luck with a product called Thoropatch.
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How do I find studs when stud finders won't work? I was trying to hang my TV at my new place, on an interior wall (between living room and a bathroom). Using the stud finder on other walls worked fine, but on this wall I got some very strange readings. An area of about 5 feet by 4 feet was setting off the AC warning, and studs seemed to be upto a foot wide and at irregular spacings. I ended up drilling "exploratory holes" looking for the stud, because it didn't make sense that there would be tens of power cables in the walls, equally spread between the studs (in the air space between, and the ones attached to the studs shouldn't be within a 1/2" of the drywall. The studs turned out to be simply 2x4s with 16" centers. Is there a trick I could have used rather than just drilling into the wall in exasperation? <Q> Do you have any high powered magnets? <S> like the rare earth neodynium magnets? <S> If so you can probably rub one around the wall until it attaches to one of the nails in the studs. <S> Or you can try thumping on the wall, a stud will sound alot less hollow versus empty drywall. <S> That's how I've searched around in the past. <A> If it moves freely after hitting it in, you are not in the stud, move 1.5" to the left or right and try again. <S> After you have found the stud, use a level or plumb bob to trace up the wall. <S> The holes will be so small and near the floor so you can easily patch or paint over them. <S> I have also removed the baseboard in the past and put the nails in there, so that the holes will be covered when you put the baseboard back on. <S> Scott mentioned magnets. <S> I have also used a stud-finding magnet, that you run all over the wall so that it will find the screws or nails that the drywallers used. <S> These nails or screws will be over a stud. <A> Try careful knocking while listening with a stetoscope. <S> Knocks on the studs will sound less hollow. <A> One way I would try is an "educated guess exploratory hole method. <S> " <S> Try locating a stud with a stud finder on the same wall, but away from the problem area. <S> Then, if you have a little bit of faith that your builder followed the standard 16" stud spacing, measure over and drill at 16" intervals. <A> Their claim is that Stud finders, particularly models with backlit LCD screens, require adequate voltage to power the sensing mechanism inside the tool. <S> Not having a spare brand-new 9-volt battery handy, I used the magnetic approach described by others here, with relative success. <S> Nonetheless, I list this approach as a possibility that has some measure of authority behind it (albeit from a company with a vested interest in having you continue to use their product).
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A variation on the "educated guess exploratory hole method" is to use a small finishing nail (longer than the drywall thinkness) and "explore" by nailing that in near the floor boards. The method recommended by a well-known maker of stud-finders is to put a fresh battery in your stud-finder .
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What is the difference between a framing hammer and a claw hammer? What is the difference between a framing hammer and a claw hammer? Can they be used interchangeably? <Q> As others have said, a framing hammer is a specialty claw hammer. <S> So what makes it different? <S> First, weight. <S> A framing hammer is typically 20-32 oz, compared with 10-16 oz for a "normal" household claw hammer. <S> That helps it pound large nails in only a few blows. <S> Related to that <S> is the much longer handle on a framing hammer. <S> Second is the face of the head: it's waffled to prevent slipping off the nail head, helping prevent bent nails. <S> A regular claw hammer will sometimes have a textured face but not nearly as pronounced, and the face may also be smooth. <S> A regular claw hammer often also has a domed face to allow a skilled hand to sink a nail below the surface with minimal surface damage: that's a feature you won't see on a framing hammer. <S> Third, the claw is straight since it is optimized for prying boards apart. <S> A regular claw hammer is optimized for pulling nails. <S> If you're only building a garage, I'd recommend using your regular hammer rather than buying a framing hammer. <S> (Or best of all, just go rent a nail gun!). <S> For inexperienced carpenters, the time spent hammering will probably not be what slows you down. <S> Also, the framing hammer is tiring enough that after a couple hours you may actually be faster with a smaller, regular claw hammer. <S> If you do get a framing hammer I recommend a lighter one. <S> You'll work faster when you use it, you won't lose much power over a heavier hammer, and you'll feel much better on the second day. <S> In 2010 if you hammer enough that a 32oz hammer makes a difference versus a 24oz hammer, you have a nail gun anyhow. <A> In my experience, framing hammers are generally larger and heavier, have a straighter "claw" and are more suited to the demands of framing. <S> They provide less accuracy but more force, which is nice. <S> And the straighter claw is good for prying boards apart. <S> If you only have one hammer, you want a claw, but if you are doing a lot of framing, a framing hammer is a nice addition. <A> Framing hammers typically have heavier heads and longer handles, and the face is usually not flat (I think the claw is less curved as well). <A> They often have a textured head, which will reduce the liklihood of skipping off the nail, but will almost guarantee that you mar the wood that you're nailing into. <S> It can also result in the nail being driven a little bit below the wood. <S> As such, it's really not useful for finish work. <S> They also tend to be larger, to help reduce the amount of swings needed to get the nail in (they're really not intended for delicate work), and have a straigher claw to get between two laminated timbers to pull them apart. <S> If you're only going to buy one -- get a general claw hammer, but I'd recommend using some sandpaper to rough up the face if it's polished smooth. <A> Framing hammers are heavy duty rip hammers with a straight claw : <S> Standard hammers have a curved claw : <S> Weight and means of manufacture have nothing to do with the differences in versatility of these two hammers. <S> Notice the juxtaposition of both of those, in both these examples, compared to the other answer's requirements; these are just a crappy rip hammer and a (very nice) standard one. <S> Length, weight and tang are key factors <S> but I prefer rip hammers that can double as a crowbar, over every other consideration. <S> It's not the size ...
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Framing hammers are a specific type of claw hammer.
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How do I remove dried paint from ceramic tiles and the bathtub? The previous owner didn't bother to lay down a dropcloth when painting the bathroom, and there are multiple, small paint stains on the ceramic tile and bathtub. What is the best way to remove them? The only thing I can think of is to scrape it off with a razor blade, but I am afraid that it will leave scratches that are uglier than the paint stains. Edit: Note that the stains are several years old. <Q> A straight razor blade shouldn't cause any trouble on your ceramic tile (assuming it has a smooth finish) or an enameled tub, but a fiberglass tub <S> you're right to worry about. <A> I personally find a Mark One Digital Manipulator does the job! <S> Seriously: use your fingernail. <S> Alternatively, choose an appropriately hard scraper of some kind. <S> A razor blade should be fine on good-quality gloss-finish ceramic tile, but I'd use a hard plastic knife of some kind on a plastic tub. <A> Takes a bit of rubbing to do it <S> but it usually pulls it off. <S> I'd recommend trying it on an inconspicuous area first to make sure it doesn't do any damage, mineral spirits is powerful stuff. <A> I used hair spray! <S> Spray, wipe and repeat. <S> It all came off! <A> I have to say I have done all of the answers listed on this page and what works the best is scalding hot water. <S> Razors can damage tile, fingernails take too long, mineral spirits and sprays are too messy. <S> Keep dousing an area with a big pot of water <S> and it will be gone in a few minutes with little work. <A> Hot water only works on latex paints if it is an oil based paint then you need to use a commercial stripper. <S> The environmental friendly ones work <S> but you have to be patient and follow the directions.
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Depending on the number of stains you're trying to remove you may find that heating the surface a bit by filling the tub with hot water then draining again will weaken their hold on the tub enough that you may be able to remove them with gentle scraping with a putty knife (being careful not to dig into the tub's surface). I've used mineral spirits to remove everything from paint to roofing tar.
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What are my options for asphalt driveway repair and/or sealing? I live in New England and my asphalt driveway is showing a lot of cracks. There's also a little divot in one flat spot that collects water. What are my options for getting the driveway back to looking good, and stopping any further damage? <Q> I'm repairing my asphalt driveway currently. <S> I have lots of cracks that grow weeds through. <S> I tried to get it sealed with liquid sealant, but within a couple of months it was clear that this didn't work, because many new weeds have grown through the sealant. <S> I think the workers who did the sealing did a really poor job, and I regret hiring them. <S> Since then, I've read several DIY articles about it <S> and I've started fixing the cracks myself. <S> Here's what I'm doing: Clean driveway. <S> I used a stiff broom, and even my shop-vac right over the cracks. <S> Clear out the cracks. <S> Remove weeds, dirt, debris. <S> Scrape <S> the crack out with a prybar. <S> Clean again with a garden hose on "jet" setting. <S> Let dry. <S> Fill the cracks with asphalt filler. <S> This comes in tubes like caulk, and I use a caulking gun to apply it. <S> I use a cheap putty knife to smooth the top of the caulk. <S> It's messy stuff, and I need to clean my tools with a powerful solvent. <S> I use Gunk, an engine de-greaser. <S> Once I have all the cracks repaired with caulk, I plan to re-seal the driveway again with liquid sealant. <S> I agree with @Scott Vercuski, wear clothes you plan to throw out. <S> I saw the workers using a pushbroom to spread the liquid, so I recommend getting a pushbroom you plan to use only for this project. <S> I also have a couple of spots where a crack has let water seep in and erode a cavity beneath the asphalt. <S> I'm going to have to chip out a section of asphalt with a hammer and chisel and restore it with with asphalt patch. <S> This might be what you have to do with your low spot. <A> Depending on the size of the cracks an asphalt sealant should close things up and protect the driveway. <S> your local home improvement store should have asphalt sealant and may have asphalt patch available. <S> Asphalt sealant is pretty messy stuff though, best to wear throw away clothes and boots. <A> Repair the cracks. <S> If water gets in, you will not stop it from causing more cracks from freeze/thaw cycles. <S> Next, use a better quality sealer. <S> Messy stuff, but it will help. <S> The problem with a low spot is something you cannot solve with a sealer or crack filler though. <S> A low spot may mean that cars parked on the driveway have caused settling. <S> (It seems silly to say that parking your car on your driveway is a bad thing, but what else can I say? <S> If you really want a perfect driveway, don't use it.) <S> Dips where your tires sit suggest that the base for the driveway was not sufficiently thick, or inadequately compacted, and over the years has sagged. <S> If this is so, then water will continue to collect in the dips, and cause future problems until you choose to have a new driveway done.
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If the cracks are large you might have to get some asphalt patch and then seal it.
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How can I pour a concrete pad with a circular hole in it? Essentially, I'd like to put down a concrete pad for a patio, but leave a couple of circular areas within that patio unpaved (for planting shrubs). I'm familiar with the techniques for using dimensional lumber for angular concrete pads, and even using plywood for curved ones, but is there a clever trick or something for creating say a 3' diameter unpaved area within a concrete pad aside from trying to bend plywood planks into a circle? <Q> Metal landscape edging (the kind that's held in with stakes) should work fairly well. <S> You could either just leave it there or cover it in plastic and remove it after the concrete sets (personally, I'd leave it). <A> This can be done using Bender Board . <S> You should be able to find it in both wood and recycled plastic. <S> When using it to form concrete make sure you use enough stakes to hold the weight of the concrete. <A> What about a Rubbermaid container? <S> The kind they have to hold ice and drinks/kegs seems about the size you want. <A> Use a upside down 5 gallon bucket, paint can, or anything that is deep enough to not get buried in the concrete. <A> A wooden barrel has a 21"-24" diameter at the head. <S> You can usually buy a half barrel at a good nursery/garden center. <S> The advantage is that you can easily dismantle it after the concrete has cured by knocking the staves inward. <A> I'd look for something else cheap that is about the correct size, cover it with plastic sheeting and use it to keep the concrete out. <S> Ideally it would be something flexible (or breakable :-)) <S> so you can get it out when you are done. <A> Styrofoam circles in the center then just knock the foam out when it sets up. <A> Why not first install some nice edging (of brick or otherwise) then concrete up to the edging. <A> John, you undoubtedly found a solution some years ago, but this kind of situation will likely surface again for other DIY's. <S> I'd suggest considering using Sonotubes, if they are readily available. <S> Yes, they typically are used for making tall columns (I've used them for building 9 foot high, 1 foot diameter pillars in an earlier backyard of mine), but they also have been used for concrete footings. <S> The only difference in this latter instance is that you are pouring the concrete outside the Sonotube, rather than inside. <S> The end result will be a well-defined, beautiful circle. <S> Sonotubes can be purchased in short lengths (expect the cost/foot to be higher for small height pieces, rather than for purchasing a full-size Sonotube), as well as different diameters. <S> Ask your local supplier (checking availability at HD Supply or White Cap would be good starting place) to either cut exact dimensions for you, or buy a long enough piece and cut it yourself, marking it first and then cutting it carefully with an electric jig saw, or keyhole saw. <S> Stake the Sonotube in place along the inside. <S> making certain that you already have in place any irrigation line and elbow (for the riser--that can be inserted following your pour) for the plant going in the circle. <S> This assumes also that you have a firm base for the bottom of the Sonotube, that won't sink when dampening the ground prior to the pour (to extend the curing of the concrete, rather than having its moisture sucked quickly out by dry ground). <S> Hope <S> this helps out future concrete pad endeavors!
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Staking can be with 1/2" diameter rebar, with lateral rebar pieces tied to the verticals, so as to hold the top of the tube in place. They use several old 5 gallon buckets leftover from construction in our basement.
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How can I remove rust stains from enamel sink? Is there a sure-fire way to get rust stains off of an enamel sink? <Q> <A> I've used CLR with some success. <S> You can also try a pumice stone. <S> The stone should be gentle enough to not scratch the enamel, but tough enough to remove the discoloration. <S> I removed hard water stains from the inside of an old toilet pretty easily with this approach. <A> I previously tried using the CLR at Scott's suggestion, and it worked to some degree, but did not completely remove the rust stains. <S> I actually found the answer to my problem this week, pretty much by accident. <S> I was cleaning a particularly stubborn patch on the tile floor, and ended up using a Mr. Clean Magic Eraser on it. <S> While I had the 'eraser' out, I figured, what the heck, let's try this on the sink. <S> It removed the rust stain almost completely, with just barely a trace of it left in a few places. <S> If I didn't already know it was there <S> , I don't think I could find it at all. <S> I'm not sure what this did to the finish of the sink, since the eraser claims to use microscrubbers, which I assume is essentially a very fine grit sandpaper plus some chemical action going on. <S> I couldn't find any trace of ill effects, and it's been about a week, and no buildup has occurred in the area I scrubbed. <A> Barkeeper's Friend. <S> It's a cleanser like Comet or Ajax. <A> I've used Lime away with a hard toothbrush; then put the stopper up and the last little bit filled the sink with an inch of bleach and let it sit ( <S> WARNING: do NOT use these two chemicals together; one at a time cause it is caustic).
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Not sure about "Sure fire" but a product called CLR (Calcium, Lime, Rust remover) is a good start.
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I added insulation to my attic rafters, but should I have left room for airflow? I added insulation to my attic rafters and plugged the space between the outdoors and my attic with insulation. It lowered my heating bill by $150/month, but I've seen some information that I may have made a mistake by cutting off the airflow in my attic. Did I make a mistake, and if so, how can I properly insulate my attic? There's already insulation in the floor. <Q> You can buy air ducts that staple to the inside of your roof above the eave vents and fit between the rafters. <S> The will hold open an air gap of approximately 1 inch to allow airflow past a layer of insulation. <S> The ones I've used are made of styrofoam and IIRC they cost around $2. <S> You should be able to find them near the insulation in your home improvement store. <S> EDIT: <S> They are called baffles or rafter vents ; this is how they're installed: <A> The point of allowing airflow to reach the outside is so hot air can escape. <S> If it doesn't escape then it will heat up the roof/rafters and cause snow to melt and then turn to ice. <S> This can damage your roof in a number of ways. <S> Also, moisture will be trapped in the attic and can cause mold or damage to the structure. <S> I believe the optimum way to insulate your attic is to insulate the floor of the attic very well but allow the air above that to escape (ie. <S> insulate the ceiling of the attic poorly) <A> There are a few different types of attic designs. <S> One is insulating the floor and venting the space above the floor with soffit (eave) vents and an attic fan or two. <S> One reason for the air flow that hasn't been mentioned is that, since the hot air will exit out the top of the roof (whether the attic fan is powered or simply turned by the force of the hot air rising), then it has to be replaced by something. <S> If your soffit/eave vents are plugged up, it will suck air out of your house, which, of course, is not good for your electric bill. <S> There is another type called the CATHEDRALIZED ATTIC, which is where the insulation is put on the underside of the roof itself. <S> CATHEDRALIZED ATTICS <S> SHOULD NOT BE VENTED. <S> Since it sounds like you have cathedralized your attic, you should not install soffit/eave vents or baffles. <A> You don't want to plug the space between the outdoors and the attic. <S> As Joe mentioned, that will cut off airflow in the attic and cause ice dams in the winter. <S> It will also keep your attic VERY hot in the summer, and raise your AC costs.
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Ideally you want a "cold" attic - lots of insulation between the ceiling and the attic, and no insulation between the attic and the roof, along with plenty of soffit and ridge vents to keep the air circulating up there.
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How do I make a lamp cord stick to drywall? Because trying to fish electrical wire through the walls and ceilings of my old house was too daunting, I have resorted to using a lamp cord to power a ceiling-mounted light from an existing outlet on the wall. How do I make the cord stick to the drywall? I tried hot glue but it didn't hold and cable clips (white plastic loops with nails) fell right out of the drywall. <Q> The wire is neither big enough, insulated enough, or grounded. <S> Use Wiremold with standard electrical wire. <S> That's why the product exists. <A> You can pick it up at Home Depot/Lowes/etc. <A> There are many sizes of conduit (also known as trunking) available that should do the job. <S> Some are even self-adhesive. <S> Also, consider that the lamp cord need not take the most direct route. <S> Most old houses have wires that go in very strange directions: I've seen some go up into the ceiling, along to a cupboard, down two floors, then back up a floor to the lightswitch! <A> You could also use a "sticky" cord management solution, such as the options on these options from 3M or others, such as this one on Amazon from GE.
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Do not use lamp cord to extend a circuit to a new outlet! Alternatively it is possible to replace the nails on cable clips with screws and drill/plug those into drywall, but the result is very ugly. It's illegal everywhere, and I wouldn't consider it to be safe. Don't - they make special conduit just for that.
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What is the best method to patch a large hole (2-3 inches) in drywall? I have a large hole where a TV wall mount once was (I believe the hole was used to run power and coax cable to the TV). I have since moved the TV and would like to patch the hole. What is the best way to do this? <Q> Correct way to do it as instructed on 'Canada's worst Handyman': cut a piece of strapping (wood) that will be a couple inches longer than the hole on each side. <S> put the strapping inside the hole and attach it using a couple of drywall screws so that it is across the hole. <S> cut a piece of drywall that is the same size as the hole, as close as you can get attach the patch to the strapping with a drywall screw mud, sand, paint. <S> Same process works for larger holes and also on the ceiling which can be tricky. <A> score the back of the drywall one inch in from each edge. <S> break the drywall at the score line, and then remove the drywall from the paper. <S> trace the drywall portion of the patch onto the wall, over the damaged area. <S> (the part that's still solid, not the paper that's 2" larger on each side) cut out along that line. <S> test plug for fit, and if necessary, clean up the edge <S> some put down some drywall mud on the inside of the lip of paper. <S> insert the patch into the hole mud over the edges <S> let dry, sand, and paint. <S> I would still use @dilbert789's answer for larger holes, though, or anything in the ceiling, but I had a few incidents of wrestling with strapping when repairing similarly sized holes (fists, doorknobs, etc.), as you need to hold the new reinforcement, the screwdriver, a screw, etc, which gets difficult to juggle for one person. <A> Use a drywall repair patch. <S> They are cheap and easy to find at the big box stores. <S> And here's a video on how to do it: http://www.youtube.com/watch?v=qvtoikKG318 <A> They sell dry-wall patches for this purpose. <A> Do you have a stir stick for paint handy? <S> Slap some thick glue on the ends and glue that in as your backer. <S> No need for screws on such a small hole. <S> If you're daring you can just mud the inside lip of the hole and squeeze a plug cut to shape in there, too. <S> But then you run the risk of it tilting all funny.
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There's an alternative to @dilbert789's solution when you're dealing with holes this small: cut a rectangle of drywall about three inches larger than your damaged area in both dimensions.
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How do I add an exhaust fan to an old attic? Our house's attic retains a great deal of heat during summer. While we now have a good layer of insulation between the attic and the rest of the house I wonder if it would be worth it to add some kind of exhaust fan. We live in a mid-Atlantic state so we have to contend with both 100°F summer days and 0°F winter nights. The house still has the original slate roof so adding a typical roof-based system isn't an option. There are three small circular windows that provide some air flow, but not much. My thought was to install a fan in one of those windows to force a cross breeze during warm days. Is this likely to save us any energy (given that the fan will have to draw some power)? Are there options for solar-powered small window exhaust fans out there? <Q> There are solar-powered gable fans - an Air Vent-brand fan can be picked up at Lowe's for just over $200: <S> The solar panel is on a cord, so it can be installed in the most sunny area while the fan sits in the gable. <S> That's because it is powered by a solar panel that collects energy directly from the sun and converts it into electricity -- naturally -- to power a durable, high efficiency 24-volt DC motor. <S> As a totally solar-powered solution, it's also environmentally friendly. <S> Painless Installation <S> The best installation feature is that the fan requires no electrical hook-up. <S> That means no electrician and no complicated wiring is required, making the installation of your attic fan fast and easy. <S> It mounts in the gable end of the home, behind a decorative shutter (not provided, see below). <S> The solar panel comes with brackets that allow for mounting on the roof. <S> Smooth Operation <S> The solar panel collects energy throughout the day under direct sunlight and converts it into "free" power to operate the fan -- providing ventilation during daylight hours, when it's needed most. <S> It creates up to 800 cubic feet of air movement per minute to remove uncomfortable heat in the summer and damaging moisture in the winter. <S> And, the solar panel is wind-, hail- and impact-resistant to stand up to the elements. <S> Specifications Moves up to 800 cubic feet of air per minute Solar panel collects and delivers power under direct sunlight during the hottest part of the day without electrical cost Wind-, hail- and impact-resistant solar panel High efficiency, <S> durable 24-volt DC motor 5-year limited warranty <S> (source: airvent.com ) <S> Model #SHT15W <S> Plastic <S> Sold in the color white only <S> but it can be painted to match a home <S> ’s exterior <S> Automatically opens when the power fan is running and then closes when the fan is not running <A> There are powered gable vents you can install (cut a hole thru the side of the attic, or use the already provided gable vent) and they're fairly inexpensive. <S> The best way to remove heat would be to use those small windows for makeup air and use a separate powered vent to exhaust the hot air. <S> The previous poster has a good suggestion about setting up a PV panel to run the fan, but in order to get sufficient airflow through the attic you'll probably need a pretty large sized PV setup which can get prohibitively expensive. <S> I've been researching them for my motorhome - the rough thumb rule seems to be ~1000 dollars per 100 watts of solar power (I added in costs for batteries and inverter since your home doesn't already come equipped) <S> Even a smallish AC powered gable vent fan is going to pull 400 watts - so you can see how this gets expensive. <S> There is a combination solar panel/attic vent kits which uses a DC motor <S> but I'm not sure about the effectiveness. <S> It seems to be rated fairly low in terms of air volume moved (800 CFM vs 1200-1600 for a 110v powered vent fan). <S> Exhausting your attic will definitely save you energy as you're removing a huge heatload from your air conditioning - the superheated air in your attic. <A> This won't answer all of your questions but it may be something to think about: <S> Consider using a solar panel to power the fan. <S> If you only need it running when it's hot (the sun is out) then it makes sense to use solar panel. <S> It can run all day long without incurring energy costs.
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From the Air Vent website : The Gable-Mount Solar Vent is an exciting alternative to traditional attic ventilation.
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Why not put a vent that pushes air from the attic into house? I have this idea, and since it seems logical to me, but I don't see it anywhere I suspect I am missing something.. so here it is: Why not put a vent that pushes air from the attic into house? At summer, everyone wants to exhaust the hot attic air outside, makes sense. Winter time, the attic still gets hotter, quicker, on cold * sunny day then my house (because I have little direct sun into my house, but also in any well insulated house). why not use the greenhouse "attic" effect, and have a vent sucking the hot air from the attic into the house? you could have that fan linked to a thermostat, only pushing air when attic temp > house temp... seems easy and cheap, what am I missing? <Q> Aside from the fact that your attic can be very dirty, you need to be concerned about the following: <S> If you have any gas heating equipment in the attic (central heat, water heater(s)), they may not meet regulations to allow them to be connected to the house's main air supply. <S> You can run a major carbon monoxide (CO) risk from improper ventilation of gas-burning equipment. <S> Pest control companies can use harsher "dusting" pesticides in attic spaces - stuff <S> you really don't want joining you in the house. <S> Insulation is often loose and can irritating. <S> If you have a much older house that might have asbestos insulation, then you have other problems as well. <S> When you pull air out of the attic, it's repopulated by the air from outside. <S> If the air outside is very cold, your attic could reach new low temperatures, freezing pipes or causing other damage. <S> (This may or may not happen, but it's something I would make sure of before attempting this.) <A> Depends on your climate I guess, but around here in the winter my roof is covered with snow and the attic is cold even on a sunny day. <A> This is called " positive input ventilation " and is sometimes done in the UK to control condensation. <S> The claim is that the air in the loft is warmer than the outside air and that by pushing it into the top landing you force out the moist air from the house. <S> Sometimes it works well in older small homes, but there are better systems for new build.
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It seems that if your attic is warmer than your house in the winter, then you either have an insulation or ventilation problem.
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How can I add/alter wiring inside single-brick walls? Our house is full-brick. Double-brick on the exterior walls and single-brick for every internal wall. It was built in 1979 (I guess they liked to do things properly then). We've only ever had the opportunity once of adding new electrical items to the single-brick walls (like a heated towel rail, new light switch and powerpoint), when we were renovating as the electrican had to chase a huge chunk out of the wall, lay the cables, and then the hole was filled back up and painted over. That's a pretty major operation. Is there any other way that we can add or modify the electrical items inside a single brick wall? We now want to run CAT5 and we've got all the external walls done, but not the internals. <Q> I highly recommend using Wiremold for this kind of project, but it depends on the aesthetics that you are going for. <S> 1/2 <S> " <S> EMT when bent properly gives a really neat look on exposed brick. <S> I really don't like the idea of channeling into brick (or block) <S> because: It never looks the same again, even when you paint it <S> It weakens interior walls, which might be more prone to crumbling / falling in an earthquake prone region than they otherwise would. <S> 500 series Wiremold should be all you need to do the job. <A> You could do something with trunking on the surface - either put in skirting with built-in trunking or try to find some trunking that matches your skirting and put it just above... <S> Then run all your cables through that. <A> Was your builder far-sighted enough to run the utilities in conduit? <S> If so then you may be able to run CAT5 through the conduit if there's enough room remaining. <S> I've just bought a new 802.11n hub and found it brilliant at going through masonry, even with regular 802.11g clients. <A> If the places where you want CAT5 are also places where you have existing CATV (RG-6/RG-58) or telephone cables, the answer is simple: <S> Securely connect a fish tape to the old cable at the wall. <S> Pull the old cable and feed the fish tape through the wall. <S> Connect the new CAT5 cable and pull the fish tape back. <S> If you've switched to VOIP or cell phones, you won't miss the old telephone wiring. <S> If you do still need that land line or CATV cable, just connect both wires to the fish tape. <S> It'll be a tighter fit but should be fine. <S> Four tips on doing this: Tape is cheap. <S> Overdo it. <S> Lots of loops and use the tape to ensure there's nothing at the connection to the fish tape that can snag. <S> Making a loop in the original cable is the best way to do it. <S> Upgrade RG-58 to RG-6, upgrade old two-pair telephone wiring to another CAT5, etc. <S> If you don't own a proper fish tape, buy one. <S> It's a flat metal wire <S> that's a breeze to feed through walls and won't break. <S> Tried to use twine and other types of rope several times, lost a few cables in the middle of walls. <S> Not fun. <A> There are many options for running data cabling on the exterior of a wall. <S> Basically it sounds like your options are limited to some type of surface-run raceway or conduit. <S> It all boils down to cost and aesthetics. <S> EMT would be code compliant - unsure about any other cabling raceway types... but every commercial building I've ever worked in uses EMT to run wiring between floors. <A> A photo would help. <S> One option it to take baseboards off and cut a cat5 grove into each one. <S> For the brick, you can chase along mortar joints between brick, then repoint and paint. <S> The cat5 cable is thin enough to not make a major deal of it. <S> If the cat5 is coming from the attic, chase the brick down to a doorway. <S> You'll find a gap behind the door jamb molding. <S> Then chase the wire next to a floating floor or behind a baseboard. <S> Or just give up and go wireless with channel bonding: http://en.wikipedia.org/wiki/Super_G_(wireless_networking )
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If you need to keep the old cable, use the opportunity to pull new wiring for it as well. Personally I think using EMT would look the best for running on the exterior of a brick wall (I love the industrial/exposed services look), but there are many other types of raceways and cable trays you could use. It may also be possible to run the CAT5 through the floor voids, then remove the baseboards / skirting and chase a short distance up the wall beyond. Using a pipe bender takes a bit of skill and practice, but can be an art form on it's own. Alternatively, if the CAT5 is for computer networking, consider wireless. Disconnect the old wiring at the network interface outside while working on it, for safety reasons. If you're set on surface mounted raceways I would honestly look at the stuff made by Panduit - everything I've used from Wiremold (generally what you find at home improvement stores) is pretty ugly imho. However if you're penetrating through a slab (running between floors) or any kind of fire barrier - you'll need to ensure whatever you're using is code compliant for running through a fire break.
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Fire hazard of exhaust fan with heating bulbs in bathroom? Our strata gave us permission to install an exhaust fan with 4x 250W heating bulbs into our bathroom. We are on the top floor and the roof cavity above us is the ceiling for the building. There are no firewalls in the ceiling. I've been told by a friend who's a licensed electrician that these items can be a big fire hazard, as if something catches fire in the bathroom and the fan is on, the fire will be sucked straight into the roof cavity. What are the chances of this happening? I can't imagine there's much in the bathroom that could catch fire. <Q> Aside from the kitchen, I would say the bathroom is one of the most likely places for things to catch fire. <S> You have: Water and electricity (never a great combination). <S> Curling irons and hair dryers (often cheaply made & get very hot) <S> Lots of flammable things (paint, wallpaper, drywall, cabinets, towels, etc.) <S> Things that go boom (hair spray, air fresheners, other aerosols) <A> I would worry more about the heating bulbs starting a fire themselves. <S> Secondly I would worry about mold, if your not exhausting your warm moist bathroom air properly. <S> I'm not sure about an exhaust fan sucking fire into the roof cavity, I guess it could happen. <A> As far as I am aware it is not normally too much of a concern as long as the bathroom is on the top floor of the house (and the air is exhausted to the outside). <S> It can be a big problem if the bathroom is underneath another habitable room as the celling would form part of the fire protection of the room above in that case. <S> Or if the air is being extracted somewhere it could get back into a habitable space (as it would carry toxic smoke into that area), but as this is damp air you probably are just going to extract it straight to the outside. <S> However it does depend somewhat on the design/construction of the building and local building codes. <S> It is possible to buy devices to close off the extract point if a fire occurs. <S> It is essential to use these devices if your ventilation system penetrates a fire rated part of the building, in order to maintain the safety of the building. <S> If you are in any doubt, I would recommend fitting safety devices suitably rated to maintain the same fire protection that you had before you started (e.g if you make a hole in some plaster board, fit a damper/cuff that is rated at least as good as the plasterboard).
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I would think the fire would have to be fairly large for this to happen, in which case the fan is probably the least of your concerns. These include fire cuffs and wraps that will crush the duct work in the event of a fire, and grilles and vents with built in fire dampers (that will close the vent if it gets hot). Make sure you follow the installation instructions fully.
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How do I repair aerated autoclaved concrete? I got an everlasting problem with a aerated autoclaved concrete (also known as "Gasbeton") wall: there's a crack that seems to split the upper half from the bottom half of the wall. I tried several time to fix it, either with the proper aerated autoclaved concrete putty and with stucco but, after some days, the crack comes back again. Any idea on how to fix it for good? EDIT: The wall is made of AAC blocks (as bricks), I have access to both sides and is an interior wall: basically it divides one former big room in two smaller rooms (kitchen and bedroom). <Q> Instead of trying to fix the crack, first try figuring out what is causing the crack. <S> You can fix a crack many times, but if you are fighting against something like water pressure (or one of the many other causes of cracks in concrete), you will never win. <A> Tha same problem is with my construction,aac blocks used in frame structure at iind floor.after two months while birla putty work was in progress ,numerious horizontal and vertical cracks appeared on plaster surface. <S> Before painting joints were caulked with crack sealant. <S> But after some time again some cracks developed on new place.thus is a matter of concern. <S> I think there are voids in these aac blocks and while blocks got shrink the air in voids release and cause cracks. <A> Tha same problem is with my construction,aac blocks used in frame structure at iind floor.after two months while birla putty work was in progress ,numerious horizontal and vertical cracks appeared on plaster surface. <S> Before painting joints were caulked with crack sealant. <S> But after some time again some cracks developed on new place.thus is a matter of concern. <S> I think there are voids in these aac blocks and while blocks got shrink the air in voids release and cause cracks. <S> I need suggestions /remedial measure for caulking of cracks developed in aac block masonry walls.
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Once you find what is causing the crack, then look to mitigate the problem somehow (proper drainage in the case of water buildup), and then fixing it one final time will take care of the problem.
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Should I replace fallen gutters? This past winter a heavy snow fall ripped two sets of gutters off our house, and I haven't had a chance to re-hang them yet. One is over our back door and it's really annoying having the running off hit you when you step out the back door, so they will be replaced as soon as I can. The other set was over top of a flower bed at an inset corner (so there is a steady stream of water during a heavy rain formed where the two sections of the roof come together). The only place the water seems to go is into the bed, about a foot from the base of the house. If I can avoid replacing them, I'd like to, but I don't want to risk a bigger issue down the road. Do I need to replace this second set? Am I risking long-term damage to the foundation or some other issue I'm not thinking of? <Q> You could be risking damage to the foundation. <S> It depends if the bed is properly graded or not. <S> If the bed is graded properly, the water will run away from the house and the foundation. <S> If not, the water could run towards the house. <S> After a heavy rainfall, see if the foundation concrete close to the dirt looks wet. <S> If it stays wet looking for long after the rest of the foundation has dried, it could mean that water is running towards the foundation. <S> If that's the case, you have 3 options: <S> Fix the gutter. <S> Regrade the bed. <S> Run the risk of your foundation possibly being affected. <A> Definitely replace the gutter. <S> Not only are you risking damage to the foundation, but if there's any wind when it rains your walls and windows will receive much more water than they should. <S> This can cause all sorts of other problems like rot, seepage, and suchlike. <A> Allowing rainwater to free fall from the roof can cause cosmetic issues, like dirt splatter all over your foundation and siding, but will also contribute to water in your basement. <S> The function of the gutter is to redirect this water away from the house so it doesn't gather up against the foundation below grade. <A> Find out the source of tha main problem then fix it before to getting worse. <S> problem. <A> This IS a problem, one that you should repair. <S> If you have a basement, then the water will seep into the ground, then look for somewhere to go. <S> You basement (if you have one) is a big, empty hole. <S> Water can navigate into it, even if the basement walls are water-proofed. <S> Water is surprisingly forceful, and very persistent. <S> The water will end up causing long term damage if you let this continue. <S> The water can cause other damage, even if you don't have a basement. <S> As that water runs off the roof and splashes down, it will splash against the house walls. <S> This may cause moisture problems of its own in your walls. <S> So just fix the gutters. <S> An immediate repair is always easier than fixing both the gutters and the problems the failed gutters will cause in the near future. <A> If you see that the water is digging a hole you can put a large rock in the way to help direct the water away from the foundation.
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Definitely replace the gutter, but before to do that make it sure the foundation is still okay and no damage around.
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Are those oscillating tools any good? Has anyone used those oscillating tools like the Fein Multimaster or the Harbor Freight version ? Are they as awesome as the infomercials suggest? What jobs are they good for? <Q> My dad has a Multimaster <S> and it's truly awesome. <S> Like any tool, there are jobs it is good for. <S> There are quite a few tasks I've found where it would have been really useful - mainly in repairs and renovations, where you aren't ripping out whole floor boards or walls or anything. <S> Those are things where a reciprocating saw, jig saw, circular saw or even a dremel tool (a cutting wheel is always the wrong angle.) <S> won't work well. <S> He used it to cut out windows of my daughter's playhouse after we put up the plywood walls, and it doesn't do a great job on long cuts like that <S> - he was cutting blind from the inside along the studs and the cuts aren't perpendicular to the sheet (but it's covered with trim). <A> (I actually asked at least partly so I could answer - so here goes): <S> I bought one of the cheap Harbor Freight variety on sale, and I can see where it would do a great job. <S> The example on some of the commercials about trimming some door frame to put in flooring is a perfect example of one thing <S> it's great at. <S> One thing that's especially worth a mention though is that it still has some arc to the end of the cutting path. <S> Not much, but some. <S> The regular blade like this: ^^^^^^^^| || || <S> ||______| is one of the best ones. <S> I've already used it to put together several projects. <S> It does a fair job at cutting dovetails - though it doesn't tend to cut super straight through 2x4. <S> The "safety" part is pretty nice - you can touch the tip of the blade without getting your finger ripped off, but you wouldn't want to leave your finger there. <S> I've also used the triangular sander and that seems to be really nice - I can see where the carbide piece would be great for removing tile cement. <S> If I am ever involved in that project you can bet I'll be using this oscillator. <S> One thing I've noticed - you really don't often notice how completely ridiculous this tool looks - it feels like holding a really long "normal" can. <S> It doesn't look or feel like any normal tool (drill, saw, etc) that's designed to be held. <S> For the oscillator it's more of an after thought - but honestly probably the best form for the tool. <S> Another thing I've discovered is that turning the cutting tool seems to be basically useless - my cuts aren't as straight or easy. <S> The only time it's really good <S> is when using one of those moon/rounded blades. <S> But I probably wouldn't get one of the more expensive varieties unless I were on a job where I was constantly using it. <A> I have the harbor freight version, and it has served me well, but I would definitely recommend the upgrade to one of the more mainstream versions. <S> I've been through 3 so far, all warranty replacements, for switch failures. <S> Even with the failures, I've been very happy with the job that the tool did and will definitely upgrade to a Fein if and when we purchase the fixer upper house we are looking for. <A> Once you have one of these, you'll wonder how you did without one. <S> I got one for undercutting door jambs to make room for flooring, but have ended up using it for a lot of little tasks I never even thought about. <S> The ability to make accurate plunge cuts is invaluable. <S> With a carbide blade, I have used one to cut through plaster wall without the remaining plaster cracking or crumbling. <S> I even used this to cut through a vent pipe in a wall where I no clearance for a reciprocating saw (though, that required 3 carbide blades and a fair amount of time). <S> Very useful for finishing a circular saw cut where clearance prevents you from use the circular saw for the entire cut. <S> Good sander especially in tight spaces or where control is important. <S> This list goes on and on honestly.... <S> The Fein unit is too expensive IMHO, the Harbor Freight I've never used. <S> I frankly don't trust the cheap harbor freight stuff, but it's true, for the price <S> I guess it doesn't matter if it doesn't last long. <S> I myself got a Ridgid from Home Depot for about $100. <S> Came with blades and a carry bag. <S> Now that I'm hooked on Ryobi's One+ line, my only regret is that the tool isn't cordless. <S> I may pick up one... <S> Overall, one of my favorite tools for its versatility... <S> it just gets used.
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Small cuts and getting into corners are some things that it's great at. All in all I'd say the $34 Harbor Freight version belongs in everyone's toolbox.
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Can I paint over wallpaper? So I have a wall that has a very hard sort of textured wallpaper. Recently though the wall suffered some damage that turned into a hole. The hole has been patched, and now we need to paint over that. Removing the wallpaper is not an option . How can I paint over this? Should I use an oil based paint or latex based (or does it even matter)? What are some gotchas to avoid when painting over wallpaper? EDIT: I'm not really too concerned if the texture shows through. I actually like the texture so it's not a big deal. <Q> Of course you can. <S> Future owners of the house will swear at you to no end, but that's their problem, right? <S> ;) <A> Make sure you remove any loose pieces, and cut out any bubbles that have formed. <S> Patch <S> any uneven spots (where you cut the paper, seams, other marks). <S> Sand the patches after they dry. <S> Use a good quality oil based primer and cover the whole wall to seal it well. <S> If the paper is a dramatically different color than your paint, re-prime with a primer that matches your final paint (so probably a latex primer the second time). <S> Paint with your final color. <S> BobVilla.com has a descent set of notes on painting over oil-based primers . <A> If removing it's not an option, you may want to try a textured paint roller to hide any texture or seams that the wallpaper has. <S> Also, you should start with an oil based primer, since water based paint and primer can actually seep through the wallpaper and loosen it from the wall. <A> I would never recommend this doing this, but this should give you decent results: <S> Pull off anything that is peeling up. <S> Seal it with an oil or shellac based primer (not water based since that will loosen the paper). <S> Once sealed, skim coat it with drywall mud to cover the seams/texturing. <S> Sand, prime again, and paint. <A> You can paint over wallpaper - we had to do that <S> when we moved into our current house - the prior owner had put the wallpaper directly on the drywall. <S> First, clean it as much as possible to remove grease, dirt, etc. <S> Remove any loose paper, although you may be able to re-glue them in order to keep a consistent pattern, <S> since you've stated you don't mind the pattern :) <S> Next, paint over with with an oil-based sealer/primer - there are some primers "designed" for painting over wallpaper, but the key is "sealer". <S> You may need two coats of this, depending on the texture and/or color of the wallpaper. <S> Now, you can fill in any imperfections, and mud over the texture if you really wanted to get rid of it. <S> You can even sand down any overlapping seams to make them less noticeable. <S> Prime over any sanded or filled spots. <S> Now you're ready for paint. <S> Finally, if you want to hide the spot and provide some defense from the next time, you can purchase plastic protectors that stick to the wall, and will prevent the door handle from making another hole. <A> Painting over paper is normal in the UK, there is even “lining paper” that is designed to be painted over. <S> There are 3 issues you may get: <S> Will the water in the new paint unglue the paper from the wall? <S> Will the new paint stick to the paper? <S> The paper will be harder to remove when someone has to, much harder if you use a oil based paint like other answers are telling you do. <S> However if you have old plaster that is likely to be damaged by removing the paper, then painting over the paper can be the best option if you don’t wish to have to have the room re-plastered. <A> I am in the middle of a similar project right now! <S> It's in an RV, where the wallpaper is over plywood, maybe 1/4", but quite soft. <S> Any scraping would damage the plywood quite a bit. <S> If I really wanted to remove the wallpaper, I would probably remove the plywood, too, but that's a bigger project than this 22-year-old RV deserves. <S> The quality of a paint job depends heavily on the preparation. <S> Remove fixtures and the face plates of electrical outlets. <S> Fill in screw and nail holes and let the putty dry well. <S> Sand smooth. <S> Use a bright light from the side to find blemishes. <S> Wallpaper is difficult to prep really well, and that means your final job won't be as good. <S> We're going to try using tissue paper in the RV. <S> First, prime and let dry well. <S> Put a layer of paint down, then a layer of tissue paper in the wet paint, then roll on another layer of paint. <S> This will cover the the blemishes in the wallpaper and provide an interesting texture in the end. <S> I don't know how it will turn out, but ask again in a few days. :-) <S> EDIT: <S> The result looked really good. <S> It is also more durable than I expected <S> (I thought it would chip easily). <S> Making the wrinkles and texture fine will make it easier to clean later. <A> You can safely cover almost any wallpaper that cannot be removed with the following method: <S> Scrape away any edges/peeling spots that can be taken away until your edges are smooth. <S> Seal and prime with <S> ZINSSER BINS SHELLAC BASED PRIMER SEALER. <S> Fill any weird areas with plaster and smooth to finish. <S> Recoat any of your fill patches with BINS. <S> Paint. <S> This will last 'forever'. <S> The Shellac base is alcohol which has a smaller molecule than any water/oil with which your wallpaper was applied. <S> It hardens to a shell that makes a beautiful paint surface for either latex or oil. <S> I have also occasionally added a roll on texture to the final paint coat to mask wallpaper texture and patterns. <S> This is of course only my opinion, but I have done it on 1000s of square feet of separate remodels with different heating/cooling/original materials/etc. <S> The BINS is a bit more expensive, but holds up the best, I have found, of all the primers. <S> Cheers and good luck!
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You can, some wall papers are designed to be painted over (I once dealt with a building that had wall paper that was designed to reinforce old plaster walls and then be painted), although most is not.
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What basic safety equipment should everyone have? When doing DIY what safety kit should everyone have (and use)? <Q> Safety glasses and ear <S> plugs (and work gloves too). <S> Get a good pair of safety glasses so they are comfortable, won't fog up, and do not scratch easily and then take good care of them <S> (just like they are regular glasses). <S> Wearing safety glasses when you are working below anything is huge to not only protect your eyes but also just make it so much easier to do the work. <S> If you are working outside then get the sunglass ones (they can double as just regular sunglasses too - <S> I leave them in my car). <S> Buy a package of the foam <S> ear <S> plugs ... <S> and use them all the time. <S> This is the other item that is huge to protect your hearing but then also make it much much more comfortable to do whatever loud do-it-yourself job you are working on. <S> You will notice a big difference between your stamina when wearing the ear plugs. <S> For instance, if you are pounding in nails, with the ear plugs in you won't notice the sound, but without them, the constant high pitched noise takes a toll on your ears (and wears you out for the job faster). <S> (They also are great for just blocking out noise to let you concentrate.) <A> <A> Suitably rated dust mask (respirator). <S> You can breath in some horrible stuff when drilling, cutting, using chemicals, etc. <A> I just have a basic first aid kit around the house and it has some typical items in it. <S> Bandages, gauze, antiseptic ointment, etc. <S> I also know where local emergency rooms are just in case it's worse than that. <S> (only had to use it once, knock on wood). <A> If doing anything electrical, or where electrical wires may be run through your walls, you should have a non-contact voltage tester : <S> They're about $10-15 , and the best money you'll ever spend. <A> A broom. <S> Clean up your area to avoid tripping/slipping/toe-stubbing/ankle-breaking hazards. <A> If you wear glasses, or don't like the feel of safety glasses, I recommend a Full Face Shield. <S> I wear glasses and like the extra protection given by my full face shield. <S> The face shield is also easy to flip up out of the way when you are looking at small details or measurements. <A> I live in a desert, so we have 45 to 60 days where the high is over 100 and 2 or 3 week runs where it is over 110. <S> You have to where the right clothes, inside and out. <S> Outside in the blazing sun, you wear long pants and long shirts, with a hat that has a brim going all the way around to protect your face and neck. <S> And even when the temperature is cooler you still need that protection from the sun. <S> Heat exhaustion hits everywhere <S> so keep a lot of water and take breaks from the sun. <S> Osha closes down jobsites here for no shade and not having X amount of gallons of water per person where there is not running potable water. <S> I know it sound funny and your feet from your house on a diy job but put face, skin, eye, ears, throat and nose, hands and feet in planning. <S> Another tip is planning the job is having the right tools. <S> Shortcuts can hurt and in the end your job might suffer as well. <A> Jeff mentioned ear plugs, but if you're working with other people, you'll often have to either shout at each other, which leads to taking out the ear plugs, then you don't put them back in, etc. <S> Instead, consider 'active earmuffs' -- they're earmuffs that have a microphone and speakers in them. <S> They'll relay the sounds from outside, unless the sound gets too high, and will then shut off the speaker. <S> For some high-pitched noises, they're outside of the sensitivity of the microphone, so you can talk clearer than no ear protection. <S> The only problems with earmuffs over plugs is that they don't seal quite as well around the head if your eye protection has really thick arms that go over the ears ... but having ear muffs and plugs mean you can use both for really noisy conditions.
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The other basic safety equipment is work gloves. An ABC rated fire extinguisher for each room containing potential fire risks, such as kitchen and garage.
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How do I build a wet room for a wheelchair user? How do I build a wet room that: Does not leek Does not have water run out of its door Is wheelchair accessible (e.g a very low slope) It is very hard to get the slope right by hand and I have need two many cases when the sleep is too steep and the water run runs into the rest of the house. <Q> A Barrier-Free Water Dam might be an option. <S> They allow the user to simply roll over them, then they spring back to their original shape and contain the water to the shower. <A> While I haven't build a space like you're describing, I have helped users of them and seen their designs. <S> If you are just trying to build a space that would allow the wheelchair user to shower, there are a number of products that are designed to make this relatively easy to install. <S> A quick search yielded the link above, but I'm sure there are other options out there. <S> These are less elegant looking than most true wet rooms, but can be highly functional. <S> During college I assisted a user of a shower like that, who thought they were relatively well designed except that the controls were not in a location a seated person with restricted arm movement could easily reach (something to keep in mind however you build it). <S> If you're building a larger space you'll need to grade most of the floor, particularly the area around the shower to avoid water pooling away from the drains or flowing toward the door. <S> This article has some thoughts to keep in mind when designing the space. <S> I've also seen spaces designed with a ridge that runs across the room that didn't cause problems for wheelchair users, but caused water to run toward one of two drains in the floor. <S> The advantage of grading the entire floor as I understand it, is that you always control where the water is going, instead of hoping it stays put. <S> This can be problematic of people with balance issues if you're not careful. <A> Rather than a slope, consider a little bit of a lip. <S> You'll need to consider who it is in a wheelchair, but if they can make it up a small bump, then add a higher threshold, and trim the door to give the necessary clearance. <S> You might also consider a bit of weatherstripping or similar, so that water can't easily get through the gap under the door. <S> (it doesn't need to seal that well, it can just be a small plastic flap on the inside of the door that comes down to meet the edge of the threshold.
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You can make a raised edge near the shower that a wheelchair can get over just make sure you don't make it too hard to get over.
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How can I paint over mold to prevent it from coming back again? The source of the leak has been fixed, however the old mold keeps showing though the new paint. <Q> Don't try painting over mold. <S> Use bleach to get rid of it first. <S> Make sure the entire area is completely dry. <S> Then use a special anti mold paint. <A> Kilz is not anti-mold paint. <S> Once the source of the moisture has been corrected, go to your local Home Depot and buy Concrobium fungicide spray. <S> It's all natural and an encapsulant. <S> It comes in a spray bottle. <S> Follow the directions. <S> This will kill the mold as well as prevent new mold from growing. <S> Once that is done you can cover the area with Zinnser Bulls Eye 1-2-3 Waterbase Primer. <S> The bulls eye IS mold and mildew resistant. <S> If you have a lot of water stains you may want to go with something stronger like Zinnser Guardz, but Kilz will not help you out in the water stains or mold issue. <A> A product called "Killz" is an anti mold paint. <S> Spray it down and let it dry. <S> The bleach should kill the mold off in a few days. <A> You need to: If possible - remove the source of dampness (not always possible) <S> Dry the area <S> Paint on a damp-seal product (many available) <S> Once dry you can paint over the damp seal. <S> Good luck <A> It's best to go with a natural, organic and effective remedy. <S> I've been in the business 12 years. <S> First use a roller, dip it in vinegar, ( rice wine or apple cider) <S> Then you have to use a special Lime Paint over a quartz-stone primer. <S> this will eliminate all mold permanently. <S> It raises the alkalinity levels in the air so mold can't grow on it. <A> I've had success using aluminum spray paint to cover old water stains on the ceiling. <A> NEVER use Borax or Bleach! <S> It does not kill the mold spores!! <S> It only removes the mold stain! <S> Use white distilled vinegar and hydrogen peroxide. <A> First use a sugar soap to thoroughly clean the surface. <S> Then obtain a mould killing chemical <S> (there are lots of them, go to your local hardware store and ask). <S> Finally, a good sand down and apply a stain blocking primer/undercoat such as those from zinsser or dulux. <S> Ideally something oil based. <S> Then a couple of top-coats of your normal paint and you should be sorted. <S> I'd recommend that particularly if it's an area that gets damp often (like a bathroom or laundary). <A> Earthpaint has a product called Lime Primer. <S> I just ordered one and will see how it works. <S> You can directly put it on mold and they guarantee that mold will not grow on the primer.
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You can get paint additives or paints that come with anti-mould compounds in them these days. You need to kill the mould spores first. Might try spraying the area down with a bleach/water mixture (I believe the ratio of 1 part bleach to 10 parts water is sufficient).
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How do I build a basement that does not leak when I have a high water level? How do I insure a basement will not leak when the site has a high water level? <Q> There are a few different ways I've seen this done. <S> Next best way is to do basicly the same thing, but on the inside of the house. <S> You bust up the concrete floor of the basement along the walls and install gravel and PVC pipe under the floor to drain the water to a sump pit where it can be pumped out. <S> Both those options are going to be pretty expensive, and probably not something you would want to tackle on your own. <S> Which is why many people opt to simply seal the inside of the walls with a product like Drylok as Scott mentions. <S> It's pretty effective if you only have minor moisture problems, but if you regularly get lots of water in the basement, it's probably not going to solve your problem. <A> In cinder block basements I've used a sealant called UGL Drylok. <S> It's a white, thick, paint that seals cinderblock walls and gives a nice white finish to the walls. <S> My parent's house has it on their walls and they haven't had a leak in well over 20 years. <S> UGL drylok is easy to install but be VERY sure to have alot of ventilation. <S> It works VERY well but has a VERY strong odor <S> and you'll have to heavily ventilate the basement while doing it. <A> @eric-petroelje has it right: you need a weeping tile system on the outside of the foundation so that water drains away from the foundation at its base. <S> Installing it after-the-fact means digging down to the footings around each wall in turn. <S> If you have a high water level, there is no product on the planet that can resist the hydro pressure from the water table. <S> You need to divert the water, not resist it. <S> While the side of the foundation is exposed there are several products you can treat the exterior concrete with: essentially spray-on sealants that will give you a first-class job. <S> I've only seen that on TV, though. <S> The three times I've helped with this kind of job the exterior sealant was not applied and there was no leakage afterward. <S> There are companies that specialize in this: <S> in my area installing weeping tile around the perimeter is a job in the 50k range. <S> My dad did it to two of his rental houses using a spade, though: it can be done if you're not a lazy GenX-er like me. <S> If your moisture problems aren't severe, and you don't want to commit to an expensive job like this, you could see if a sump pump solves it for you. <S> Essentially you dig a 1 ft square hole in the basement floor, down about four feet, and install a pump to discharge accumulated water outside before it becomes a problem. <S> That's a solution somewhere between the DryLok approach and the weeping tile.
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The best way is to trench around the outside of the foundation down to the footer, seal the outside of the wall, and install a drainage system (gravel and pipes) at the footer to redirect the water to a sump pit where it can be pumped out.
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How do you remove a lot of wall tiles? How do I quickly remove a lot of wall tiles without damaging the wall? <Q> I tried the screwdriver and chisel technique with some tiles in a flat in Brighton... and quickly gave up once I found there were three layers of tiles there! <S> So I invested in a cheapish power chisel - like a hammer drill, only it doesn't go around - and finished the job in a weekend. <S> If you go this route, it's definitely worth buying ear defenders and a good strong set of goggles as tile chips are sharp. <S> I used my chainsaw helmet and got a couple of dings in it. <A> Grind out the grout then pry out the pieces with a chisel or just a beefy flathead screwdriver. <S> Once you have one out, you should be able to use a chisel or a flat head screwdriver to get under the other ones. <S> Put the screwdriver under/against the edge of the tile and tap it with a hammer and the tiles will (usually) just pop off. <S> Some will be more stubborn than others, but if you're reasonably careful you shouldn't damage the wall much. <A> I used a small crowbar and sometimes a hammer. <S> The backing was failing, so it was painfully easy to ram the bar down and separate the tile. <S> The task took me less than an hour, undoubtedly aided by the failing backing. <S> Per previous comment, protective equipment is a must. <S> I used ear-protection, eye-protection and a dust-mask. <S> UPDATE: Since my first answer, I had to do another room for someone else. <S> I used a small pneumatic hammer with 3" shovel bit (chisel). <S> I used the hammer in my right hand and a putty-knife in my left (to keep the chisel off the cement-board), and this allowed me to move VERY quickly. <S> Even though I was wearing a full-face breathing apparatus, my forehead got several small cuts because the air-hammer shatters so much of the tile. <S> If that's a concern, I'd stick with a small crowbar / flatbar (the same I'd use for removing wood trim from walls).
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Typically I hit the first one (kind of gently) with a hammer until it cracks/shatters.
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Is there a standard height and depth for stairs? Is there a standard (or a standard range for) the height and depth of each step in a flight of stairs? If your answer refers to your building code, please say where you live. <Q> The general rule (in the US) is 7-11 (a 7 inch rise and 11 inch run) <S> (17.78cm-27.94cm). <S> More exactly, no more than 7 3/4 inches (19.7cm) for the riser (vertical) and a minimum of 10 inches (25.4cm) for the tread (horizontal or step). <S> You can find some more information here as well on other stair-related dimensions. <S> To calculate if the steps will be within the Building Codes specs : 2 times the step riser height + 1 tread width equals between 24 and 25 in inches (60.96cm and 63.5cm). <S> example: (2 x 7.5") <S> + 10 = 25 (2 x 19.05cm + 10 = 48.1cm) <A> <A> Not what you asked, but for safety the most important thing, even more important IMO than getting the right rise and run, is that every step is consistent. <S> Varying <S> as little as 1/4 inch in rise will make even a ballerina fall on her face if she's running up the stairs. <A> It not so much about the rise and run lengths specifically ,but about the ratio of the Rise to Run. <S> You should strive to hit a 30-35% ration of rise/run. <S> A 7-11 is the most common and gives you the correct ratio, but any combination of rise to run that hits this 30-35% ratio would be fine. <A> As a general rule your stairs should be built with this in mind and you won't bust code no matter where you live. <S> 2 risers plus 1 tread must equal a minimum of 24" and a maximum of 25" when added together. <S> Example ( 2 risers of 7-1/4" = 14-1/2" <S> then your tread could be 9-1/2" to 10-1/2").
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The Stairway Manufacturing Code Association published the International Residential Code (PDF Link) in 2006 which tells you just about everything you could ever want to know about stairs, including: minimum headroom depth (6' 8") minimum tread depth (10") maximum rise (7.75") maximum tread depth variability (3/8") maximum rise variability (3/8") maximum slope of riser (30°)
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How can I remove a single cracked floor tile? How can I remove a single damaged floor tile without damaging the surrounding tiles? Is there anything that will help the replacement tile from cracking in the same way? <Q> There is a dremel tool called the multi-max that I have used before. <S> You can get a diamond attachment for it that will cut through grout like butter. <S> Once you get the grout out you should be able pop up the tile and replace it. <A> I'd grind <S> /scrape away the grout first and then gently tap the middle of the tile with a screwdriver until it shatters and chip it out. <S> It'll probably take a while to do it <S> but you should be able to scrape/chip away the old thinset, apply new thinset then regrout. <S> best of luck ! <A> YOu can cut out the grout with a grout saw. <S> Be sure to not try to pry the tile up on the edges because you can easily damage the edge of the adjoining tiles. <S> It you lightly tap the tile in the middle and break with a hammer, you can then remove the tile from the middle area, working to the outer edges. <S> You must remove all old thin-set by chipping or grinding it away. <S> Apply new thinset to the back of the new tile and place. <S> Wait approximately 12 -14 hours than grout the new tile into place. <S> Thankscaptainbay <A> It’s important to make sure that you don’t chip the surrounding tile. <S> You can then use a rotary tool or a utility knife to cut the down-ward facing tabs on three of the four sides. <S> Be sure to use the appropriate care and safety equipment when using the rotary tool or utility knife. <S> Next carefully remove the broken tile by lifting and pulling away the uncut side. <S> Then, remove the downward-facing tabs on three of the four sides of a new tile with a utility knife. <S> Next apply a layer of adhesive and set the new tile into position.
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The first step is to remove the grout around the broken tile using a grout cutter.
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Is it a good idea to pay for an energy saving audit of my new home We have a newly built home but I'm not at all confident in the builder's prowess when it comes to energy conservation. Is it worth hiring someone (like our energy provider or other specialized contractor) to do an energy audit? Or do you think they would most likely find something whether or not there was a problem so they can charge us more for the fix? If no energy audit, does anyone have any tips for the best ways to look for these "leaks" myself? <Q> A lot of utility providers will provide a basic home energy audit for free. <S> If this is the case, it's a no-brainer. <S> If they don't provide an actual audit, then they often provide statistics for what an average home should be consuming, so you can assess if you think you're using too much. <S> Besides for that, you can check for drafts or cracks in windows and doors yourself as a basic audit. <S> After that, I've found just be living in my home, I can tell if a room is too hot or cold compared to the rest of the house, and then look for problems then. <S> With all that said, I think that you should take a long view. <A> You can hire a company to scan your house with an infra-red camera. <S> I've never hired one <S> so I'm not sure of the expense <S> but they'll go around your house with the camera and see where cool (or hot) air is escaping and give you report about it. <S> I'm sure it's a few hundred dollars to get it done <S> but it might be worth it if you think you have some major leaks. <A> Lowe's has a thermal leak detector for $40. <S> I've never used one, so I can't give you an idea of how well they work, but the Amazon rating for this one is 4.5 out of 5 stars. <A> Here is another alternative that you may want to look into. <S> Microsoft Holm . <S> It is a web site designed to help people monitor and improve energy performance. <S> They have interfaces with some utility companies, and you can buy a device to monitor your usage and send it back to the service. <S> Ir you can enter it manually. <S> Pretty slick.
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If you have no free audit options, and you can find an affordable paid service, it'll most likely be worth it in the long run.
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How do I add more circuit breakers once the breaker box is full? My house was completely rewired by the previous owner. They tore out all the old knob-and-tube and replaced it with modern wiring. I definitely appreciate this, but unfortunately they left absolutely no extra space on the new breaker box. Every single slot is filled with a circuit breaker. It's not that the circuits are doled out too liberally either. Its just a small breaker box. It fits the requirements of the house exactly, but leaves no room for future expansion. So, what are my options for adding more breakers? Can I add a sub breaker box? Or should I just replace the whole thing with a larger one? <Q> The only reason to replace the entire box is if aesthetics: if there isn't enough room on the wall for two boxes, or the box is in a closet or cabinet where there isn't physical space. <S> Putting in a new breaker box is much easier than replacing an entire box. <S> If you replace the entire box, you will need to rewire every breaker. <S> When the original box was wired there was lots of slack on each wire, but after each breaker was installed the wires would have been trimmed. <S> A good electrician will allow slack in the wires for reconfiguring breakers, etc. <S> but if it's a small box you may not have enough wire, or you may end up running the wires in ways that aren't as neat or professional as it should be. <S> With a new box, on the other hand, you only need to remove one 220V or two adjacent 110V breakers. <S> The old wires can be run into a junction box to provide as much length as you need for wiring into the new box. <S> As Mike Sherov noted, you need to be sure that your service can handle the load and number of circuits. <S> That'll be a location specific code issue. <S> If the knob-and-tube wiring was recently replaced I'd be surprised if the old service (probably 50 or 60 amp) wasn't upgraded as part of that process (likely to 150 or 200 amps). <S> If your new circuits are within the capacity of your service and local regulations permit, this is a job you can do yourself. <S> (In some places of course, they're too busy for such questions.) <S> Or you can research it yourself: it's not difficult if you have access to a code book. <A> You have two options: use tandem breakers Install a sub panel <S> There are caveats with both routes. <S> When using tandem breakers on a 120 volt system (i.e. with a neutral present), you want to avoid something that is called a multifeed. <S> This is, two circuits on the same phase sharing the same neutral. <S> When using tandem breakers, its very easy to inadvertently do this. <S> If you are in the US, you will see two feeders from the meter, one of them probably has some red tape on it, the other is black. <S> These are your phases. <S> Normally, every other breaker is on a different phase, but tandem breakers put both circuits on the same. <S> Take care that both circuits attached to a tandem have their own neutral (white wire). <S> They aren't much different from a regular panel except: Ground and neutral conductors are isolated, not bonded on sub panels <S> You want to watch your loads <S> You'll want to be careful about where you place the breaker that feeds a sub panel, so that you don't develop a hot spot on the main panel bus. <S> For instance, you don't want a 100 amp sub panel breaker right in the middle of a water heater and an air conditioner. <S> In either case, I really recommend calling an electrician. <A> It really depends on how many breakers you intend on adding and what level of service you're already getting. <S> Most of the time, the number of circuits in your breaker box corresponds to the level of service you're getting. <S> Personally, I'd recommend getting an electrician for this to calculate your energy needs. <S> However, if you know you have adequate power, and you're only interested in adding one or two circuits, you can use piggy back breakers to split the space normally reserved for one breaker into two. <S> As always, make sure you're using parts that are specified as appropriate by the manufacturer. <A> If you replaced all your singled up breakers with tandems that should plenty of space to add in any extra circuits allowed by code. <S> That's really the only way you can get additional circuits into your breaker box short of replacing the entire service.
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Assuming your service can accommodate the additional circuit(s), you can install tandem circuit breakers to replace your 15amp circuits - basically two breakers siamesed into a single breaker form factor. If you choose to do it yourself, in some jurisdictions you can ask the inspector if your plan will keep you in code, to save the cost of a consultation with an electrician. While you might be able to install a tandem breaker yourself (I highly recommend calling a qualified professional), you will surely want an electrician to install a sub panel.
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Do they make a non-liquid concrete/mortar color additive? I've been trying to find a cement additive to change the color of some mortar, but only seem to be able to find it in liquid form at my local big-box hardware store. I'm looking for a similar product that can be added to dry mortar mix. Does this even exist? Where can I find it? Back-story:I put down a patio of pavers a few years ago and apparently didn't put down thick enough plastic sheeting underneath. I skimped because the area seemed too shady to promote much weed growth. Boy was I wrong. I have major weeds growing through the cracks between the pavers. My plan is to power wash the patio to get most of the sand out between the pavers, and then replace it by sweeping dry mortar over the patio and then misting it so it will harden and form a barrier for the weeds between the pavers. To get the color right I'd need to mix the color into the dry mortar before spreading it. I'm not sure how well this will work, but I am going to try on a small area first to see how it goes. If anyone sees any major pitfalls with this plan, please speak up in the comments. <Q> What you're looking for is called an integral color and is typically done with pigments. <A> The shows I've seen have had great results with it. <S> Looks like you just throw it over wet concrete and let it soak in. <A> I have worked with dry color for concrete. <S> We poured a few slabs and some curb. <S> The dry power was available at a concrete supply house. <S> It was expensive, but could be bought in small bags if needed. <S> A little went a long way. <S> The color powder made a huge mess and stained everything. <S> It was the consistency of powdered sugar. <S> You need to mix it really well with the dry mortar or you will end up with varying color. <S> You need to test the color by mixing up and curing a sample as it is hard to know exactly what the color will look like until it cures. <S> In this case, I would skip the color and use polymetric sand. <S> Something like this: http://alliancegator.com/2011/?p=21 <A> Sakrete sells a concrete coloring in powder form which is available at retail home improvement stores like Home Depot and Lowe's, and probably Ace Hardware as well. <S> It comes in one pound boxes, and costs about $6-$7 a box, and they suggest a one pound box per 80 pound bag of Sakrete. <S> That of course would be up to you and the desired color you're looking for. <S> However, that gets pretty expensive if you have a large project that requires 20-30-50 bags and you can't use a redi-mix company due to access concerns! <S> I know there are a couple of other companies that sell bulk bags (100lb) and are available generally at concrete companies (like Redi-Mix). <S> The biggest concern is matching the entire project: you're going to need to weigh it out or measure it somehow to maintain consistency. <S> A little bit off doesn't really matter because the weather will eventually match it; however, if you're 15 shades off, weather isn't going to correct it. <S> I've seen many homeowners use it for landscape curbing <S> and it worked out very well. <S> It's very important that you mix it very well with the concrete prior to adding water to the mix <S> or you'll have less than perfect results, guaranteed! <A> Don't know how helpful this will be, but colouring concrete used to be called "oxide" or "oxide powder" when I was growing up. <S> Came in a plastic bag and was mixed into the cement powder with the sand. <S> I recall my father using it. <S> You might need to find a builder's supply yard to get it.
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Here is a source that I've used for other projects: http://www.directcolors.com/concretepigment/ I've seen powder concrete colorant on home improvement shows but to be honest I've never used it.
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Which communication bus systems for home automation? Many communication systems have been proposed for home automation (e.g., HVAC control, alarms, access control, light control, and entertainment), including 1-Wire and X10 . Which system is best suitable for a beginning home automation DIYer, especially in terms of the variety of low-cost devices available? <Q> Beside 1-Wire, protocols like RS-485 , and CAN bus are also good option because they work well on large distances (tens or even hundreds of meters). <S> Protocols like i2c or spi, are usually reserved for shorter distances (few meters) and are useful for say sensor to micro controller communication. <A> I've been very unsatisfied with X10-based automation systems. <S> I've installed a bit of it in my home, and find them flakey. <S> Smarthome's Insteon is a combo powerline/RF system that at least should be less flakey than X10. <S> This is what I will probably try next myself, since it's backwards compatible with X10 and fairly inexpensive. <S> Beyond that, there are Z-wave systems like Leviton's Vezia RF+ which look pretty interesting, but they're pricy. <S> And I hear people say great things about UPB products, but again, they cost about twice what Insteon goes for and are powerline only. <S> In my house, I think an RF component is a good idea because each half of my house is on a separate electrical box. <S> Insteon also makes every component a repeater, which is helpful in my house again because there are some walls filled with concrete. <S> For me, anything that can repeat a signal is a good thing (at least I hope). <S> One complaint (~2006-2007) with Insteon was reliability of the devices themselves, but I understand that this has improved. <S> My experience researching home automation is that you can get excellent solutions by spending a very large amount of money (tens of thousands of dollars). <S> My suggestion is to build out slowly so you don't sink too much money into a single solution before finding out what really works in your house. <A> Asking which bus to use is the wrong question here. <S> What you should be telling us is what you want to do, and then the technology to do that will follow. <S> One problem I've found is that to get the best stuff, you have to mix and match technology. <S> For example, Insteon, Z-Wave, and UBP are all leading for lighting/power control, but if you insist your security system has to use the same technology, you're going to have to pick from the best of the security systems that use that bus, not from the one that best meets all your actual security system needs. <S> The nice thing is though, there are a lot of both hardware controllers and software out there that can integrate various things together, so even if your actual security sensors are hardwired and/or some proprietary wireless protocol, you can still likely get at the least alarm conditions and at best full status/arm/dearm control onto your lighting network using addd-on products designed for that. <A> I just answered a similar question about lighting automation options here . <S> If you're going to be in a home for a while, invest in something that won't drive you crazy. <S> RadioRA is controllable by just about every third party home automation system. <A> In my experience working on industrial automation/energy management systems I found that "open" communication protocols just don't work when you attempt to mix/match components from different vendors. <S> Every manufacturer cooks up their own flavor of Modbus, Profibus, etc which has been customized for their use cases over time - you can see how this can get ugly really fast. <S> I can't speak for the residential/consumer market but back in the day every DDC manufacturer sold a "open communication protocol" gateway. <S> In my experience they were all flawed. <S> Either the controls feature set was gimped, the data wouldn't report correctly to the front end or you would issue control commands which "disappeared" when communicating through the gateway. <S> If you want to spend tons of money on an automation and datalogging solution, let me know - I can set you up with a nice server/client based front end with field panels and terminal devices communicating via ethernet. :)
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It seems that X10 is simplest solution if applicable, because it relies on existing electrical lines. For reasonable money, there's no one great answer, but there are answers that work pretty well.
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How do I discharge the capacitor of my refrigerator? In order to avoid electric shock, I need to discharge the capacitor of my refrigerator before working on it. How do I do it, and where can I buy an appropriate power resistor? <Q> Use a light bulb. <S> Besides being more than capable of dissipating the power, it has the bonus of telling you when the capacitor is empty since the light will go out. <S> The best way is to use a spare light socket and touch the two wires to the capacitor leads. <S> Lacking a socket, some wire and electrical tape will do the trick if you're careful. <A> There are special shorting probes made for this purpose, but the only ones I've seen online are for really large applications (like attached to a hot stick type large). <S> When I was in the Navy we had some nice handheld sized ones for using inside equipment cabinets. <S> Short of purchasing one, there are instructions on the web on how to build one. <S> I wouldn't just take a wire or leads from a bulb socket and short <S> the cap leads to ground - those compressor <S> start/run capacitors can be fairly high in capacitance and hold a decent amount of energy. <S> If you decided to create a DIY shorting probe, ensure you get a resistor of sufficient size <S> so you're not just instantaneously discharging the cap to ground (basically creating a direct short - unsafe). <S> And lastly... <S> ABSOLUTELY check the circuit is deenergized at the capacitor terminals after you're done discharging them <S> - you might think it's dead... <S> but sometimes you don't always get a good contact on the lead or fully discharge the component. <A> You would need a 20,000 ohm 2 watt resistor. <S> Not sure if the big home stores would have that though. <S> Might need to call around or check with an appliance repair shop.
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You should be using an insulated shorting probe to properly discharge that capacitor.
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How can I tell if wood is properly dried? I guess measuring it's weight would be one of the answers, but it doesn't seem practical because wood of a same type can probably fluctuate in it's density enough to make measurement unreliable in 10-20% moisture range. Are there any specific tips for wood like ash, beech or oak? <Q> Your best bet is to get a moisture meter, like this one: <S> Amazon link to one meter . <S> Moisture meters come various ranges: you want one that measures in the 6-14% range or so. <S> Anything above 14% is not useful for woodworking as it will shrink too much. <S> Meters come in two varieties, pinned and pinless. <S> The pinned meters measure stick two electrodes into the wood about 1/4" and measure the electrical resistance. <S> You tell the meter what species you're measuring, and it uses an internal table to tell you the moisture content. <S> The pinless variety won't mar your wood, but they're quite a bit more expensive. <S> They use induction or ESP or fairy dust or something to read the moisture level. <S> If your wallet is glued shut, you can use weight to measure the moisture content. <S> Have a look here. <A> The meters suggested are very useful, but there are a couple caveats to be mindful of when using them: They can only measure the moisture level to a certain depth. <S> If you have thick lumber <S> the center may have higher moisture content that what you read near the surface. <S> Different meters read to different depths. <S> They can't indicate if the wood was dried "properly" as you ask in the title. <S> For example defects such as case-hardening, checking, or other internal stresses can be caused by improper drying techniques but would not become apparent until you cut into the wood. <S> You might want to check out the excellent book Understanding Wood by Bruce Hoadley from your library. <A> Just do a google search for "Wood moisture meter" and that'll tell you what the moisture content is.
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If you really want to be sure there are moisture meters you can purchase.
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How do I fix a squeaky floor below my carpet? I have a squealy floor below my carpet on the 2nd floor of my house. It sounds like the subfloor under the carpet is moving up and down a little and makes this awful load squeak when I step down on this specific location. It can be reproduced at will. <Q> Fixing a squeaky floor beneath a carpet is a fairly complicated process that's probably best illustrated with video. <S> This Old House provides a wonderful tutorial. <S> The procedure demonstrated at that link does not require you to pull up any carpet and uses scored screws to hide your work. <S> This seems to be the most hassle-free way to do what one might expect to be a huge job. <A> If there's movement you'd do best to pull back the carpet and nail down the subfloor. <S> Hopefully the squeak isn't in the middle of the room. <S> I had a squeaky floor at an old house, had to pull back a large chunk of carpet and drive a few nails through the floor to anchor it down. <S> Best of luck. <A> Putting more nails is a temporary fix. <S> Screws will hold tight and resolve the issue for a long time.
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The squeak is due to flooring sliding up and down on nails that have loosened with time.
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How can I improve the water pressure in my shower? I recently purchased my first home. It has two bathrooms and the water pressure in both is less than ideal. What are some steps I can take to increase the pressure? <Q> This is an effective trick a plumbing contractor once told me. <S> Go to your local home improvement store and buy a cheap shower head (the one I picked up cost $1.50). <S> If you look down inside of the showerhead you'll see a washer which constricts the water flow. <S> If you take a drill and enlarge the hole, thereby increasing flow, the water pressure will increase. <S> I didn't think it would work <S> but it did!! <S> I've heard of such a thing but never looked for one. <A> In the U.S., shower heads are required by government regulation to restrict water flow in order to save water and energy. <S> By law, they must deliver less than 2.5 gallons per minute. <S> For this reason, many shower heads will deliver less than ideal flow and/or pressure. <S> To get around the law, and benefit those with less-than-stellar water pressure, many showerheads (e.g., the Waterpik I recently bought) come with instructions for removing the flow regulator. <S> If you've discarded those instructions, a quick Google search should be all you need to figure out how to remove the flow regulator in your shower head. <A> Low pressure can be caused by old galvanized pipe, which often build up deposits causing the water to be restricted. <S> Another cause of low pressure can be incorrect pipe size. <S> I like to run a 3/4" trunk line with 1/2" legs to fixtures (which I think is pretty common). <S> Some houses have pressure reducing valves on the supply line, which are used to control the water pressure inside the house. <S> Here's a video explaining how to adjust this valve. <S> Start by loosening the lock nut. <S> Next turn the adjustment screw. <S> Turn the screw Clockwise to increase the pressure. <S> Turn the screw Anticlockwise to decrease the pressure. <S> Once the proper pressure is set, tighten the lock nut. <S> These answers all assume the pressure is low in the whole house. <S> If it's just the shower see the other answers. <A> One thing to check before replacing items is the inline filter (if present). <S> When my shower was performing poorly, I unscrewed the head and found a small mesh screen in the line that was clogging up. <S> I cleaned it out and screwed everything back together to find my pressure right back where I expected it. :) <A> Is it the water pressure for the whole bathroom, or just the shower that's sub-par? <S> Before I bought a house, my last apartment had really poor pressure in the shower, but the bathtub faucet was fine. <S> I removed the shower head to see if that was the cause, and <S> sure enough, there was plenty of water pressure in the shower, it was just the cheapo shower head that the apartment had installed. <S> I bought a Waterpik and it solved everything. <A> Every Lowe's or Home Depot and other places like that have a shower head that looks something like this <S> and I find I get a much more satisfactory result when I have low water pressure. <S> It's just got a concentrated, small diameter of holes, and solid brass insides. <S> They tend to run anywhere from 4-12 bucks depending on where you go and what brand is available in that store at that moment. <S> Anyway, while they don't increase the flow, and they don't increase the pressure, they seem to at least concentrate the flow and improve the experience, and you don't need to alter them. <A> Nearly all shower heads sold in the USA are fitted with self adjusting pressure regulators manufactured by one company. <S> The purpose of the regulator is to maintain a constant flow of water exiting the shower head regardless of the pressure entering it (30-80 psi). <S> The problem with their design is that the regulators easily plug up with solids in the water. <S> When they clog up, the pressure and the flow rate entering the shower head are reduced and the resulting spray is weak. <S> This will happen regardless of the pressure upstream of the regulator, so raising the water pressure entering the home will probably not affect the performance of the shower head. <S> In addition, the regulators are always found inside the shower heads and are nearly impossible to reach for cleaning. <S> The solution is to find a shower head that will not clog up and will deliver a full, strong spray over a long period of time. <S> I know a little about shower heads, as I am the founder and manufacturer of a very unique shower head. <A> You can make sure that there are no water flow rate restrictors inside the shower head. <S> These can usually be pried out (I've done this on hand-held shower heads, too; <S> see also this video ): <S> Or you might need to drill a bigger hole in the water inlet of the shower head (which I've done on larger shower heads). <S> Remove restrictors in the shower valve / install bigger plumbing <S> Even if you hack the shower head itself, your flow rate might be limited by the piping / valve of the shower itself (cf. <S> this video ). <S> Also, in the U.S., it's federal law <S> that shower heads must be rated < 2½ gallons per minute! <S> See Jeff Tucker 's Hack <S> Your Showerhead: <S> Or How to Get the Government Out of Your Home and article . <A> If you have well water, the pressure in the holding tank may not be correct. <S> The cut in and cut out pressures may need to be calibrated. <A> Try the trick that was mentiond about widening the plastic hold in shower head this also works for the airators in sink fauset if it doesn't help then consider replacing the shower body. <S> If its only in the bathroom if it's the hold house then check water heater and or boiler psi.
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Remove flow-rate restrictors in the shower head If you want to go the expensive route, there are pumps you can purchase that will attach to the piping and add pressure to the water.
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What are some ways to wire rear speakers in a home theater system? I have two rear speakers, that I never use, since I don't have a good way (yet) to wire them. I have a hardwood floor. And the side of the room that is nearest to the TV+Audio source is open. So I don't have a wall to run the cable next to it. <Q> You can then punch holes in the top of the wall where you need to run vertically, fish the wires through, staple it up into the corner, then install the crown molding to hide everything. <S> You can also go the low route, and hide them behind your baseboards, but there isn't always a void behind them, so this could get a little messier if you have to trim away drywall (or plaster in older homes) to create a channel you can use. <S> You also have problems with baseboards if you have to go past any doorways. <A> Have you thought about using in-ceiling speakers? <S> Then you could fish the wires through the ceiling (assuming the joists run the right way or you have access to the attic). <A> Easy setup + affordable wireless solution are now available. <S> There are a few soundbar systems with a set of wireless subwoofer and rear satellite speakers <S> For example the Vizio S4251W-B4
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If you're installing in room where you can't drop above or below the room to run your cables, consider putting up crown molding -- it typically leaves a small channel behind it which is ideal for hiding speaker cables.
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What is the best way to remove popcorn from the ceiling? What is the best solution for removing popcorn from the ceiling if I want to get it to look smooth afterwards? Edit : thanks for your answers! Would you estimate that replacing the drywall on the ceiling would be less work/mess and result in a better finish? <Q> My wife and I just finished doing this last month. <S> Here's the process we took: Before you start, check to make sure you don't have asbestos in the popcorn. <S> If your house is newer construction, you don't have to worry about this, but if it's older, you may want to scrape a bit off the ceiling and send it to a lab for testing . <S> If it comes back positive, I would have professionals handle it. <S> Otherwise: <S> Cover everything you don't want to get gross and disgusting. <S> Turn off breaker for the lights and remove fixtures. <S> Use a spray bottle or a garden sprayer to wet 5' by 5' sections of ceiling with water. <S> Be careful not to oversaturate it and damage the drywall. <S> Scrape off popcorn with a 6" or 12" taping knife, whichever you find easier to handle. <S> Sand any spots you missed that are still rough. <S> (For the most part, everything comes off smooth.) <S> Apply mud liberally to any gouges you made. <S> Most spots I had to go over were at the seams of the drywall. <S> Sand again. <S> Repeat 6 and 7 <S> if you're OCD like me. <S> Prime Paint with 2 coats of ceiling paint. <S> Throw away <S> drop cloths Lie on the floor and stare at your new smooth ceilings :) <S> One bit of advice: You're going to make A LOT of dust, and it will get all over everything in your house that isn't covered. <S> We did the whole process before we moved in, so we only had to wipe down the walls and floors. <S> After you're all done, you'll probably want to change your air filter as well. <A> We just put some new drywall directly over (under?) <S> the existing ceiling. <S> It was a lot easier and cleaner than trying to take it off. <S> This was in a bathroom, though, so the area wasn't too big. <A> Unfortunately, you're going to have a really hard time removing it. <S> The usual solution is to make a couple passes over it with a drywall knife to scrape off the highest spots, then skim coat the whole ceiling to make it flat again. <A> I had a co-worker who removed his popcorn ceilings by sanding them down (I'm not sure if it was a drywall sander or just a big sander) and then repainting them. <S> He didn't get them entirely smooth, so it looks like they were retextured.
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Wipe down the ceiling to get rid of any sanding dust. If you want to get everything super smooth, shine a flashlight or work light parallel with the ceiling to find raised/gouged areas.
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What do-it-yourself cautionary tales do you have? I'm curious what sort of cautionary tales everyone has come across (or experienced themselves). For instance, my dad used to work on live wires all the time — until he was putting a stove in (220V if you don't know) and touched two wires together. The spark flew off and hit his glasses and melted about halfway through the lens. He still works on live 110V, but he always turns off the 220 circuit now. What about you? Any (hopefully just-as-happy) shocking experiences you folks have had? <Q> I once had a tenant who lived next door in our duplex and thought she could hook up her own gas drier. <S> Smelled gas one day and couldn't find where it was coming from, so I knocked on her door. <S> Walked in and the whole place reeked of gas. <S> Checked the drier, and sure enough, the supply line was barely even screwed on. <S> Asked her about it and got one of those "Yeah, it's been like that for a while <S> now, was going to ask you about that" kind of responses. <S> Lucky it didn't take out the whole neighborhood. <A> Treat your router like a loaded gun, it has a ton of power and can shoot things with a lot of force if you aren't using it correctly. <S> Consider that a router runs at around 24,000 rpm <S> compare that to... <S> A table saw: ~4,000 RPM <S> A drill: ~800 <S> RPM <S> The feed direction and double checking that the bit is securely locked into the chuck is critical if you value your life and/or limbs. <S> If it is making a funny noise, stop immediately and check it, even if it is a pain in the butt. <S> Just once, I shot a loose bit across my workshop at terrifying speeds. <S> I always check thrice since that day. <A> Well, I had one that more so lead to a DIY project then happened during. <S> Commercial building built in the 1930s, had lamps hanging from ceiling by chains. <S> One day I'm changing a light bulb and someone walks in and flips the light switch. <S> It threw my arm back, almost knocked me off the ladder, and my hand was spotted black for a little while. <S> The wiring running through the chain to the lamp was cloth insulated and had broken down over the years. <S> Needless to say, I spent the rest of the day rewiring all of the lamps in the building. <S> So, be mindful of working in old buildings, even on the simplest of tasks. <A> If you're doing a job that creates a lot of dust, it's really worth tarping off the doorways to limit exposure. <S> After doing a floor sanding project, for the next few months my laser printer smelt like a fireplace every time I printed something. <A> And when you do snip them, even if the power is off, make sure your hands are insulated. <S> We had an electrician swear to us that he had disabled all the power to one part of the building, but even so I felt a tingle <S> so I went and confirmed with him that the power was off. <S> He rolled his eyes and said yes. <S> So I got my snips and cut through the wires. <S> BANG! <S> Lots of sparks and some very loud swear words. <S> Thankfully I just happened by pure chance to have my hands insulated. <A> Be careful when walking/working in your unfinished attic... <S> it is very easy to miss a beam and put your foot through the ceiling. <S> Best thing to do is use a piece of plywood if you need to work up there for any extended period of time. <A> Never leave wire ends unprotected, even for a moment. <S> It's too easy to get distracted and forget to replace a wire cap or crimp a connector. <S> And once the junction box (or wall!) is closed up, it's too late, and <S> some day later you cause an electrical fire. <A> Most of my DIY experience and interest is in electrical matters, so the stories I have are from that. <S> The people who built a house I have improved did alot of things themselves to save money - which I don't look down on! <S> What I DO is the way they did certain things. <S> Probably the most annoying thing was to route a line through a switchbox that did not feed anything. <S> Turning off all the power to the lights the switches fed was not enough to prevent a strange tingling feeling. <S> I will admit this was many years ago <S> and I was less experienced and felt more invulnerable. <S> I also admit that I should have questioned all the cables entering the box, since I then would have noted the odd one. <S> Another one that still gets me is people using a white (NEMA color code) coated wire as a hot line and not marking it. <S> I've fixed that many times.
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Always, always, always, always, always make sure the power is off before snipping 240V power cables.
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How do I nail furring strips without them cracking? While remodeling my basement, I had several walls where I just put up furring strips and foam insulation rather than framing in a "real" wall. I used 1x2 furring strips and attached them with a ramset and 1 1/2 inch nails. Problem is, putting the nails through the furring strips would quite often cause them to crack. I tried pre-drilling (didn't really help) and also tried using 1x3 strips in some places (helped a little, but not much). Is there some trick to nailing up furring strips to keep them from cracking on you? <Q> You may be using the wrong load. <S> This site recommends using a Yellow #4 load on strips 3/4" thick, or Green #3 for 1/4" - 1/2". <S> You could also use concrete screws. <S> Pre-drill holes in furring strip and wall (about every 24"). <S> Clean holes in walls <S> well (with shop-vac). <S> Using concrete screws fasten furring strip to wall (do not over tighten). <A> I figured out a workaround for this. <S> Today, rather than using actual furring strips, I just ripped a sheet of 3/4 inch plywood into strips on the table saw. <S> Being plywood, it doesn't split. <S> Not an ideal solution, but worked out pretty well for me. <A> As an aside, remember that basement concrete walls are not watertight, so when the ground is wet, the interior concrete may get moisture on the inside. <S> Furring strips directly against concrete is a good way to end up with wet wood, which means mold and rot. <S> Same goes for where the basement floor meets the studs. <S> Full framing an inch or so from the wall with foam insulation behind is better for keeping the finished wall dry, even though you'll lose some interior space. <A> Also look into using construction adhesive to attach the furring strips and then fewer masonry screws. <A> When you hammer a nail through a strip of wood, the point of the nail splits and goes between the fibers of the wood. <S> Instead, take each nail as you use it, put the head on a firm surface and tap the point once or twice with your hammer. <S> This will flatten the point so that instead of splitting the fibers of the wood it cuts the fibers of the wood as it penetrates and is thus far less likely to crack the board. <A> Is there some trick to nailing up furring strips to keep them from cracking on you? <S> SKL has hit the nail on the tail, dull the tip first. <S> That technique reduces splitting of all types of lumber. <S> Keep your fasteners away from the ends of the boards. <S> When the nail is being driven into the concrete, it tries to escape sideways, stressing the furring strip and frequently cracking it. <S> The force is enough to split 2x4s if you didn't pay attention to tip #2. <S> Unless you've got a system in place (sill gasket) to prevent your concrete walls from wicking moisture up from the footings and the dirt against the outside of the walls (vapor barrier/membrane/drainage gravel), your plywood strips <S> will get moist. <S> Then they'll mold and delaminate. <S> If you're using marine grade plywood, it'll take a bit longer. <S> While doing some demo work in a basement, I found hardwood flooring glued (one quarter sized glob per foot) and nailed to the walls where it had been fastened 65 years prior. <S> It was still in very good condition. <S> Pine would have long since fallen victim to moisture and rotted away. <S> After pre-drilling holes, I'd wager that most any hardwood will resist the forces of a concrete nail without splitting.
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Pre-drilling the holes would typically prevent splitting, but not so much with concrete nails. Instead of furring strips, use 3/4 hardwood flooring.
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Is it worthwhile to have ductwork cleaned? Was rearranging some ductwork in my basement, and noticed that the stuff I took down was pretty filthy inside (especially the return air ducts). Is it worthwhile to have ductwork cleaned out? What kind of (if any) efficiency benefits do you get out of it? <Q> It's not the efficiency which you get -- it's less dust in the air. <S> Less dust equals better health in the long run. <S> Lots of dust in the ducts is an indication of a bad air filter and/or leaks around the filter or in places where ducts join/turn. <S> I'd look for that as well. <A> Here are the EPA guidelines for duct cleaning and when it is necessary. <S> http://www.epa.gov/iaq/pubs/airduct.html <S> Keep in mind that the airflow ducts usually aren't as bad as commercials would have you believe, unless the system was run without an air filter. <S> The filter usually sits in your air return, which makes sure any air flowing into your supply ducts is "clean". <S> So, if you see a lot of crap in your supply ducts, you probably have unfiltered air entering the system (hole in a duct maybe). <S> The other way stuff gets into the supply ducts is from people dropping crap into the floor registers. <S> If it's dirt in the registers, you can usually get it out by lifting the register and sticking your vacuum cleaner's hose in there. <S> Just be careful that you don't gouge or hit the sides of the ducts, which can damage them (they can shed fiberglass). <S> You may have stuff in your return ducts (animal dander, etc), but because of the air filter, this usually doesn't affect the overall air quality in the house much. <S> The exception would be if you have something in the ducts that the air filter won't trap (mold spores, smelly things). <A> For me it was. <S> The house I live in now was previously owned by animal owners. <S> I'm allergic to animals and there was a ton of junk in the air ducts so the cleaning got rid of a lot of junk in the air. <A> Areas with high humidity can grow impressive mold collections, particularly on systems that have humidifiers as well. <A> Duct board systems should not be cleaned . <S> They will rip and send more junk into your air. <S> However a metal duct system can be cleaned. <S> If you use a good filter you should never need to. <A> The previous owner of my house did some remodeling and did not do a good job of containing the drywall dust. <S> The furnace and ducts were full of it. <S> I had everything cleaned and now there seems to be less dust in the house and the temperature coming out of the duct seems to be warmer for the heat and colder for the air conditioning. <S> I would say it was worthwhile in my case.
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Depending on your location mold build-up (in addition to the dust mentioned by others), can be a big reason to clean the ducts.
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How can we fix bouncy floors? Our floors are somewhat bouncy, especially in big rooms with long joists. I think that the main cause is that they used 2x8 joists on 15-20' spans. We are going to replace/install hardwood in several areas. Given that we'll have access to the subfloor, what can be done to make the floors less bouncy? Note: looks like it's different from the situation described in What are these spongy/soft spots on my hardwood floor? , since the floor moves as a whole and not just in some places and there are no hollow spots there. <Q> It might be worth checking out the subfloor <S> if you can get access to it in case that is what is not holding up to weight instead of the joists. <S> Otherwise, I know in your comment you stated that you don't have the joists exposed, unfortunately, I don't know of a way to resolve the issue without exposing them as anything you tried to do at the floor level <S> would just be adding weight. <S> If you don't feel your joists are up to snuff, you can reinforce them by laminating them. <S> You would get additional boards of appropriate size to fit snugly next to the joists, then use an adhesive and screw the boards to the joists. <S> Make sure you are getting the additional wood over your load bearing walls, otherwise again you are just adding weight to the situation. <S> Remember though, even if you are going to make it a DIY project, structural work is a big deal and you should at least consult a contractor/architect and make sure you get proper permits and inspections. <S> You can save yourself the money on the labor, but don't skimp on the planning. <A> ManiacZX mentioned laminating the joists below, and in my opinion, if you had access to the joists, you'd be better off installing bracing between them (cribbing, bridging, whatever you want to call it) ... <S> but that assumes that you actually had access to the joists. <S> but it flexes less ... <S> I'm not sure how MDF compares to plywood on flexibility), and then screw it down tight to the original subfloor. <S> (and a lot of screws -- might even be worth renting a belt fed screwgun, as you're going to want them every 6" (15cm) or so to make sure the new subfloor is bonded well to the existing one, so they flex as a single unit. <S> If you can get the floor stiffer, it'll distribute the load better across multiple joists, and therefore they should deflect less when loaded. <S> ... <S> Your other option is to come in from the top -- strip the existing subfloor off, install the cribbing, then lay the subfloor back down. <S> Depending on how the subfloor is laid, you might be able to cut windows into it (set a circular saw so it just barely goes through the sheet; you might have to drill a hole and use a wire <S> w/ a bent end as a guage first), expose enough to set the cribbing, close it back up, then to the lamination thing I mentioned above to stiffen the subfloor. <S> ... <S> It's possible that installing the hardwood floor might help to spread load better (especially if it's laid <S> so it's perpendicular to the floor, and nailed in, rather than a floating floor), but it'd really suck to go to the work of laying the new floor, and then have to tear it up because it's still a problem. <A> Really, 2x8? <S> That's undersized for a 20-foot span, even if your house is old enough for full-sized lumber. <S> 15 foot would even be iffy in my book for a 2x8 (though I'm not a structural engineer). <S> Like Mike and ManiacZX, I would recommend tearing out the subfloor and laminating the existing joists across the entire span, both for better carrying the load and helping to decrease the give in the flooring. <S> Modern flooring is much less forgiving than, say, old hardwood floors. <S> If you have large spacing of joists and sistering still doesn't get you down to 16" OC or less, add bracing as Joe recommended. <S> Also, use two layers of new subfloor, perpendicular to one another and fastened with both lots of screws and adhesive to one another and the joists. <S> Also, especially if this is an older home, check the level of the home itself--that may be one source of the problems. <A> A 2x8 joist on a 20' span is extremely undersized. <S> What is the center-to-center spacing of your joists? <S> If I were you <S> I'd seriously consider pulling up the subfloor at least in the center third of your longer spans, and sistering in extra joists as described by ManiacZX.
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as you're going to be gaining access to the subfloor, you might be able to stiffen the floor as a whole -- put down some adhesive, lay more plywood/chipboard on top of it (ply's more expensive
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Should I replace or repair my dead/dying garage door? My garage door opener is on its last legs, should I replace it or try to fix it? Symptoms: The door does not initially move when the button is pushed, but after giving the door a boost it opens. The door works fine on its own, it is definitely a problem with the motor. The motor does not start when disconnected from the door, but giving it a boost makes it spin. So this has nothing to do with the door. I have worked with electric motors in the past but am far from an expert, and in most cases when dealing with them it was a huge pain in the neck. I'm guessing this is a problem with the brushes, but have never opened up a motor from a garage door opener before so I'm not sure what to expect. Can these things be repaired, or is it cheaper and easier to buy a replacement? <Q> Lots of things can be wrong with your garage door or opener: <S> It could be something as simple as needing to replace the springs. <S> If they are torsion springs , you're going to want to consult a professional, as they can store a deadly amount of tension. <S> Consider it as dangerous as electric repairs. <S> Some garage door openers operate on battery. <S> You might need to replace them. <S> Some garage door openers have adjustable settings. <S> This is probably not the problem because you've noticed a degradation in performance and haven't indicated fiddling with the settings at all. <S> It could be a misaligned track, causing unnecessary work for the motor. <S> If all else fails, it's the motor. <S> It's cheaper to replace it! <A> I know you've checked the door <S> but here is how you know if the door is okay . . . <S> disconnect the garage door opener and open the garage door half way. <S> If it stays there then the garage door is balanced, otherwise there are problems. <S> Sure, the motor could be burned out but if the door isn't balanced the replacement unit will burn out too! <S> If the unit is old I would replace it. <S> Lots of times it's not just the motor but the gears inside too. <A> As a Garage Door installation professional, my first check is (as you have done) to make sure the door works with the GDO disconnected; if it passes this test then you can have high confidence the GDO is indeed having problems. <S> First we always look at the age of the opener: all openers have a label, generally on the side or back of the unit, which tells you the year of manufacture. <S> I generally advise that if an opener is 10 years or more in age then it is time to look at replacement. <A> Are you sure the door still moves smoothly? <S> That opener does NOT have enough power to move the door if something is wrong. <S> Try disconnecting the door from the opener and make sure it moves smoothly (springs still good <S> an in adjustment, all wheels move smoothly, etc). <A> Get a can of aerosol electronics cleaner and hose the motor out. <S> There may just be some dust, gunk, or spider eggs binding it up. <S> If that fails see how easy/cheap it is to just replace the motor. <A> I have had the same problem. <S> In my case I opened up the housing, and it was filled with a lot of plastic shavings. <S> It turns out the shavings were the main gear which was made smooth over time. <S> I replaced the gear and have had no problems in the last 4 years. <S> It was around $20 for the kit to fix it.
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Try a simple cheap fix first.
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What is the best way to repair a cracked bathtub? Close examination of the floor of my bathtub has revealed a long, thin crack in the bathtub itself. The bathtub is one of the common plastic-feeling variety (though I am not sure if it is actually a plastic.) What is the best way to patch this crack? <Q> Most bathtubs that aren't cast iron or steel are acrylic plastic. <S> If the crack is right through the tub and water is leaking though, you should replace the tub. <S> If it's an emergency and you need a short-term repair, I'd use a two-part epoxy. <S> Choose a thin epoxy (2:1 ratio) from the selection at the home center and use a putty knife to try to force it into the crack. <S> Let it cure for 24 hours. <S> This will be at best a short term solution because if tub cracked it must be because it flexed in that spot - it will flex again and the brittle epoxy repair will crack again quickly. <S> The problem is color matching: your tub will have changed color over time and it will be difficult or impossible to get a good match. <S> Another approach is using fine sandpaper. <S> You can get very fine wet-and-dry sandpaper at an auto parts store like Napa. <S> Get 320, 600, 1200 and 2000 grit. <S> Apply some elbow grease to the scratch with the 320. <S> Try to keep the scratches localized and in one direction. <S> Use the 320 until the scratch is gone. <S> Then move to the 600 and keep it up until the scratches from the 320 are gone. <S> By the time you're done 1200 you may be satisfied, but if not you should be able to get a fairly glossy finish with the 2000. <A> If your crack is at the bottom of the tub <S> and it is acrylic or fiberglass <S> then most likely the crack will affect the structure of the tub. <S> In order to do a lasting repair, you need to repair the structure. <S> You can take a two pronged approach: Step 1) <S> Drill relief holes at either sides of the crack. <S> Then drill several small holes around the areas of the tub that flex the most when you step on them. <S> Buy some expanding foam for "Gaps and Cracks". <S> Spray it into all of the holes as far as it will go. <S> The point is to provide some support under the floor. <S> Wait a day and then sand down or physically remove any foam that expanded above the floor of the tub. <S> Step 2) <S> Purchase a repair kit that includes fiberglass mat(s) and resin. <S> The fiberglass will provide a new structure and the resin will bond it completely with the old surface. <S> Do not expect color matching at this step. <S> You will most likely need to do another project if you care about color matching. <S> However, now your repair will be structurally sound and will very likely last a long time. <A> You might think about replacing the tub.
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If the crack is a surface scratch, it can be repaired with a repair kit such as offered by http://www.surface-repair.com/ .
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How can I paint over a glossy surface that might contain lead paint? I am repainting a bathroom that includes trim with a high gloss. The house is old (1924) and the existing paint may have lead in it. There was a remodel in the '80s, but I can't guarantee the current paint was applied then. My local paint store advised against sanding to take off the gloss, because of the lead risk. They recommended a "liquid sandpaper" product which I applied. However, the first coat of the new paint did not stick (I've been stripping it back off for the last couple of weekends). The paint store also advised I did not need a primer, which I now believe was a mistake. How can I get the new paint to stick to the old? <Q> Rather than just seal in paint that might be lead-based, especially as you mentioned that you're stripping off the bad coat, it might be worth finally just removing it <S> so you don't have to go through these concerns in the future. <S> (especially if you don't have kids now, but think you might in the future, so you can get the dust over and done with). <S> New York has some recommendations for removing lead paint . <S> The important thing is to keep it from becoming dust and getting spread around the house, which just makes things worse. <S> I believe there are some chemical paint strippers that can be used with lead paint, although that website didn't mention any. <S> I also found mention that Massachusets used to require licensed contractors and require it to be disposed of as hazardous waste , so it might be worth checking before you attempt this. <S> ... <S> If you were going to attempt this without stripping it all off, I'd follow the New York guidelines (contain the area), wet sand to rough up the surface, then prime it and re-paint. <S> Odds are, being gloss and trim, it's more likely though, and even if the top coat isn't, there might be lead in an older coat. <A> Eric's comment is the best advice. <S> The less you know, the better. <S> Here are the three options that I would consider: Heat strip at low temperature (<1100 degrees) <S> Paint over with a good primer. <S> Replace the trim <A> Replace the trim, if you're really that concerned. <S> Will probably be easier and cheaper than dealing with any more paint stripping. <A> Read up on EPA Lead Safe Practices at https://www.epa.gov/lead/renovation-repair-and-painting-program
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Oh ... and you can also get test kits for check for lead paint.
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Can I lay pavers over a concrete patio? I have a concrete patio in my backyard that's in pretty good condition. We don't like how it looks, so we'd like to cover it up with brick or pavers. Looking online, it appears that most people install pavers over gravel, so I was wondering if it was a good idea to lay the pavers straight on the concrete patio. Would drainage be an issue? What kind of cement would I use to secure the pavers on the concrete? <Q> If you have a drainage issue, or you're likely to have freezing conditions, I'd personally want to lay a small coating of gravel across the concrete <S> first - allow that pent-up water to get out of the way. <S> If you're building this in, say, Phoenix, though, that may not really matter and laying them directly atop the concrete shouldn't be a problem. <S> To the 'cement' part of your question: why not go with dry-laid? <S> As long as there is some form of rim to the patio, or you're not driving over them, dry-laying would make both maintenance and modification easier. <A> Gravel would make that worse. <S> You are going to have to brace the pavers to keep them from shifting. <A> I would not put pavers on top of concrete. <S> I was going to do that (I live in Illinois) <S> but my contractor said NO. <S> He ripped out the old concrete patio and installed pavers (Unilock) and it looks fantastic! <S> I believe in the long run, the cost of replacement is well worth it as opposed to putting pavers on top of a concrete slab. <S> Your concrete slab might look decent now, but over the years it will will eventually crack all over and become uneven due to the constant freeze/thaw cycles over the years, so you can imagine what will happen to those pavers if they are on top of that patio. <S> Like another poster said, if you live in a temperate climate, it probably would not hurt to put pavers over a slab.
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If you are not in a freezing condition, then the only other problem I see is that the pavers will shift on top of the concrete pad.
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Why does my toilet intermittently run continually? I've pretty much fixed up my bathroom since moving in. The last bit of annoyance now is this: Not every time, but every 10 or so flushes, my toilet will run continually. It'll sound like it's water is filling up for about two minutes, then stop for five minutes, then sound like it's filling up again... on repeat. To stop it, I have to go back in and jiggle the handle. One time I took the lid off the top of the toilet and it looked like it was slowly losing water from the top (or whatever it's called). Any idea on how to fix this? <Q> I would first try to replace the flapper, it may be old and worn and not creating a proper seal. <S> If that does not work try replacing the ballcock (float valve), as these too can become old and worn and not function properly. <A> Then the water can continue to "leak" out and eventually it might trigger the tank to start filling again ( <S> on windy days you might see it happen more as the wind blows and moves the water in the toilet and tank). <S> You should be able to adjust the arm that attaches to the float so that the shut off happens and the level of water is below the top of the "tube" (not sure what that is called). <A> I have also found that buildup of minerals or iron by-product can foul up the mechanism that lets the float detect the water level. <S> I have a lot of crud in my water because I'm on a well. <S> Harmless, but smelly. <S> So I have to take apart the toilet mechanism about every month or two and scrub <S> it all out.
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If the water is leaking from the top, then you probably have the shut off level too high (the level set where the float eventually rises and shuts off the flow of water into the toilet tank).
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What should I use for a sandbox bottom? I'm building a sandbox for my three-year old. It will probably sit on the deck, so it needs some kind of bottom. Ideally, we should be able to move the sandbox around the deck. Is it necessary for water to drain out of the sandbox, or will the sand absorb enough water? What should I use for bottom? Ideas: Landscape fabric: allows water to drain through, but may not be strong enough to move. Regular plywood: allows movement, but may rot and does not drain. Redwood plywood: I don't know anything about, but I saw it at Home Depot, and it may be more resistant to rot. Edit: Combination: plywood with a few drilled holes, covered by landscape fabric. <Q> Since you are going to place it on a deck, move it around, want to keep water and cats out, I would just buy a plastic one with a lid. <S> In my opinion its not worth the hassle. <S> The wood alone will make it heavy and hard to move around, let alone with sand in it. <S> They are fairly cheap, we bought one a few weeks ago at a garage sale for $5. <S> I know there is pride in doing it yourself <S> , I wanted to build one too, but in the end, it may not be worth it. <A> The sand will definitely not absorb/release enough water if it's ever open to the rain. <S> If your box doesn't drain, you'll have a small pond (as we do if we ever forget to put the lid on). <S> Your landscape fabric idea sounds pretty good. <S> I'd just build that on top of decking slats or something like Trex (which might be perfect for this). <S> Some gaps between the slats will allow drainage. <S> Look into what the decking material is treated with. <S> I'm in the camp that believes that the fears of CCA pressure treated wood are overblown, but even I probably wouldn't use it in a sandbox for a three year old. <S> Keep in mind regarding sliding it around: Sand is heavy, especially when damp ( 100-130 pounds per cubic foot ). <S> We have a pretty small plastic sandbox in our yard <S> and I can't move it without dumping the sand first ( <S> but then "small" to me is something that holds three boys :D <S> and I'm sliding across grass). <S> Those will require that your base be much more rigid of course. <A> I used a linoleum remnant for my kids and it lasted for 20 years. <S> Now I can't find a remnantanywhere for my grand kids' sandbox. <S> The linoleum worked great as it could still drain out the bottom and it kept the sand clean as they did not scrape up dirt when building their "roads" in the sand. <A> Just thinking off the top of my head maybe a wooden (cypress) frame, put a metal grid across the bottom (maybe some kind of galvanized grid) and brace it with some pieces of cypress. <S> Then put the landscape fabric over the metal grid and then fill with sand. <S> I almost said go with a straight metal grid but <S> the weight of sand and children would probably be too much so the pieces of cypress would brace across the metal grid. <S> This way you'd get good drainage and the ability to move it around (if you put it on casters). <S> Not sure how resistant redwood plywood is to rot or if they make cypress plywood. <A> Use a tarp with lots of tiny holes poked through it. <S> I used a meat tenderizer to poke the holes through. <S> I simply cut it to size and stapled it to the bottom. <S> Works great :) <A> Once sand was put in the weight would keep you from being able to move. <S> Here is a great design to keep critters out and let the rain drain thru. <S> Jae <A> I thought of these good ideas but In my case the sand boxed area is enclosed outdoors and the ground is covered with pea gravel. <S> Instead of removing the gravel I kept it as it has a cushioning effect for the knees and drains water thru to the soil beneath. <S> After much thought I decided on the exact size piece of a well woven rug remanant BUT turned it upside down as the threads were so tightly secured only minimal sand can seep through. <S> Then poured in 7 bags of white sand. <S> This is working great so far. <S> Should moisture cause mold <S> I'll bleach the entire sand box. <S> It appears that the layer of pea gravel causes the carpet and sand to stay somewhat aerated. <S> So far my twin grandsons are loving it and are even able to add a "little" water without causing a big mess! <S> So what do you think?Just me, Lisa
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I thought of putting outdoor remnant over the top of the sand as they could lift it and the cats and squirrels couldn't dig in it. Landscape fabric because even if you was to put wood which would rot. Landscape fabric always easy to get and replace. You might want to think about furniture glides if you can find something that will slide reasonably on your deck, or even castors.
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Can I have multiple heating zones with a combination boiler? I bought my first house in December and one thing I've noticed over the winter is higher than expected gas usage which I'd like to try and get down if at all possible. The house is a three bedroom (two plus box room really) semi-detached UK house built in the 30s if thats relevant. The previous owner had recently installed a new Ideal Icos HE24 combination boiler but with a standard thermostat and timer. I'd like to replace the thermostat and timer with two programmable thermostats for upstairs and downstairs and use valves to control heating flow to the two zones. I've seen drawings on the internet showing this using a standalone boiler with separate pumps wtih each zone but am not sure if zones are achievable using combination boilers or whether I'd be placing stress on the boilers internal pump? My thoughts so far involve one valve for the upstairs flow and one for downstairs flow, from what I've seen I don't need return valves as well? Working with heating systems isnt something I've done before so I guess I may have some things wrong here but would be interested to hear peoples thoughts. <Q> As long as the boiler is capable of providing enough hot water through the system to heat the whole house if necessary you shouldn't have a problem. <S> What you are proposing is a "coarser" version of thermostatic valves on each radiator and that is perfectly safe for a combination boiler. <S> I don't think you need return valves. <S> Make sure that you leave one radiator "open" (usually the bathroom one) so that there is some flow around the circuit. <S> By the way the fact that it's a combination boiler is a red herring. <S> The "combi" bit refers to the hot water heater, the central heating aspect is pretty much the same as a "standard" boiler with integral pump. <S> Update <S> If you want to control the times each room is heated independently you can get combined timer and thermostatic radiator valves - My Greener Home has some for example. <A> Just putting thermostatic valves on each radiator is the standard solution these days. <S> However having zones will you set each zone to come on at a different time as well as giving them their own thermostat. <S> You may not even need to add a 2nd pump if you design the system carefully. <S> Remember <S> last winter was very cold by UK standards, so it is not a good indication of ongoing gas usage. <A> I am not an expert on the subject, but when we were buying our house, inspector noted that heating system has three separate pumps for the three zones. <S> He said, that it was "nice", and "more reliable then a single pump". <S> From this I draw a conclusion that it is possible to run multiple zones off of a single pump, but you probably want to avoid doing that. <A> More than one zone is the ideal solution and will be far more efficient than using radiator valves however not so easy to accomplish in an existing system depending on access to your plumbing. <S> Zoning is achieved by using a solenoid valve for each zone - 2 in your case after the pump. <S> You only use one pump. <S> The Thermostats - 2 in your case control the solenoid valve. <S> So when your downstairs thermostat calls for heat it opens the Solenoid valve <S> , the pump starts and your boiler goes into action. <S> Same for upstairs. <S> They are completely independent. <S> I have put an extra zone in my conservatory with its own Thermostat so when its cold outside I can keep the conservatory at a toasty 21deg with one radiator without affecting the rest of the house.
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You can do anything with a combination boiler that you can do with a system boiler of the same rating.
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Is basement smell caused by oil boiler? Although dry and not moldy, my 130-year-old basement has a distinct basement smell that bothers my wife. I am trying to determine its source. We have steam heat. In the summer, the boiler is only used for hot water, of couse. Do oil boilers usually smell? The boiler is seven years old. It was inspected by the oil company and given a clean bill of health when we moved in a few months age. <Q> Hard to say without smelling it, but it's likely moisture (even if it's dry) or just poor air circulation. <S> First thing I would try would be putting a dehumidifier down there to see if that helps. <A> (although some people are more sensitive than others). <S> Possible smells from an oil furnace: If you have a leak in a fuel tank, or some other spill, it will smell like diesel fuel. <S> If your chimney doesn't draft correctly, you could get smoke inside the house, which leaves a greasy smoke everywhere. <S> (like the exhaust from a badly maintained diesel vehicle) <S> If you don't get your furnace cleaned and inspected, you can get a condition where it burns hot. <S> (there was a jet of flame shooting out of the inspection port), which can also get smoke inside the house. <S> If you had water radiators with a circulation pump, if not maintained or it breaks a seal, the wear can cause an oil burning smell <S> Luckily, I haven't had the first one -- that took months for my neighbor's basement to vent because their oil company overflowed their tank. <S> I think there was still a lingering smell for a year, as it had soaked into the concrete. <S> (the soot thing sucked, too, but once I scrubbed down the walls, it wasn't so bad). <A> They make a powder, for oil spills that helps with the smell. <S> Smells like carpet fresh. <S> Just light dusting and let stand .Sweep up and sucks up fuel and fumes.
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As someone with an oil furnace -- when running properly, the smell of an oil furnace shouldn't be significantly noticable.
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