document type doctoral thesis author sedumedi, thomas dipogiso tshipa email @ example. com urn etd - 10172008 - 170856 document title first - year students ' use of prior knowledge in the learning of acids and bases degree phd department curriculum studies supervisor advisor name title prof a hattingh supervisor keywords - accessing knowledge - knowledge restructuring - incomplete knowledge - quality of knowledge - generate meaning - knowledge construction - inhibiting effects - prior knowledge - error prevention - types of knowledge date 2008 - 09 - 03 availability unrestricted abstract science has been perceived as difficult to learn because of its nature and the methods by which it is usually taught. most first - year science students entering higher education in south africa today come from disadvantaged teaching and learning backgrounds. these students bring different “ knowledge, skills or abilities ” into the learning process. this knowledge, referred to as prior knowledge – or what the student already knows – is the single most important factor influencing learning ( ausubel, 1968 ). it is on the basis of this influence of prior knowledge on learning that the focus in this study is on understanding its manifestation in learning. prior knowledge has both facilitating and inhibiting effects in learning. however, the focus in this study was only on inhibiting effects of prior knowledge on learning. to better understand prior knowledge qualitative methods ( interview, observation, document review and the prior knowledge state test ) were used. the aim was to specifically establish how students used their understanding of selected acid - base concepts and processes to construct understanding and to generate meaning of new concepts and / or knowledge. the study managed to highlight important aspects of the quality of prior knowledge and their manifestation in learning. the findings generally indicated that : - the quality of the knowledge that students possessed was in most instances incomplete. that is, in their description of concepts, students preferred to use summary and informal descriptions without understanding the meaning of the concepts they were describing. - the quality of knowledge ( e. g. incomplete knowledge ) affected their ability to construct understanding and / or generate meaning as this knowledge was insufficient to access for the construction of scientifically valid meanings of concepts. - the quality of students ’ knowledge impeded their ability to reflect and / or to be aware of the knowledge they possessed. this made it difficult for students to access knowledge and to restructure it in order to construct new knowledge or prevent errors in their learning. the study culminated in the development of a framework that may in future be used to assess prior knowledge and enhance meaningful teaching and learning based on


discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field. 5 posts • page 1 of 1 although biology is the science of life, biologists have not yet been able to define “ life ”. although molecular gene is the foundational atom of modern biology, the “ gene ” also remains undefined. likewise “ species ” is the foundation of evolutionary biology, but evolutionists ( including darwin ) have not been able to define “ species ” yet. it is without knowing these, biology is ‘ advancing ’. is biology on the right track? if it is, why we are unable to get clear understanding of these things in spite of substantial research already done in biology? we do not pause to ponder over this issue. it is high time we at least doubted something is fundamentally wrong in biology. it is without knowing what “ life ” is, we are trying to create life. the basic reason why we cannot define or understand the phenomenon of life is the erroneous concept of biological information. molecular gene ( genome ) concept is wrong. biological program responsible for life and the functioning of an organism is not encoded by a chemical molecule ( dna ). by treating dna as the molecule of life, we are superimposing biological information over chemical information. this implies that dna is the only molecule in the whole universe that carries biological information over and above chemical information. this is wrong. the molecular gene concept is therefore flawed and is scientifically untenable. it is violation of chemical principles. the scriptures lend a helping hand to resolve the issue. just because the help comes from scriptures, we should not reject it. that is unscientific. but if the scriptural revelation cannot be proved scientifically we can reject it. the quran and bible reveal that life is nonmaterial phenomenon validating the original proposal of ‘ nonphysical gene ’ by wilhelm johannsen in 1909. he warned against two things while proposing the gene concept ; one is against treating gene as material entity, and the other is against assigning gene for particular character. both these warnings have been since proved correct. the nonphysical biological information can be conceived on the lines of computer model of the organism. phenomena of life and death can be defined and explained in the light of the quranic revelation based on the computer model of organism. the quran informs that god created adam by “ breathing rooh into a clay model of man ” ( q. 15 : 28 - 29 ). the term nafs is also used in place of rooh in the quran


water droplets and light form the basis of all rainbows, which are circular arcs of color with a common center. because only water and light are required for rainbows, one will see them in rain, spray, or even fog. a raindrop acts like a prism and separates sunlight into its individual color components through refraction, as light will do when it passes from one medium to another. when the white light of the sun strikes the surface of the raindrop, the light waves are bent to varying degrees depending on their wavelength. these wavelengths are reflected on the far surface of the water drop and will bend again as they exit. if the light reflects off the droplet only once, a single rainbow occurs. if the rays bounce inside and reflect twice, two rainbows will appear : a primary and a secondary. the second one will appear fainter because there is less light energy present. it will also occur at a higher angle. not all the light that enters the raindrop will form a rainbow. some of the light, that which hits the droplet directly at its center, will simply pass through the other side. the rays that strike the extreme lower portions of the drop will produce the secondary bow, and those that enter at the top will produce the primary bow. the formation of the arc was first discussed by rene descartes in 1637. he calculated the deviation for a ray of red light to be about 138 degrees. although light rays may exit the drop in more than one direction, a concentration of rays emerges near the minimum deviation from the direction of the incoming rays. therefore the viewer sees the highest intensity looking at the rays that have minimum deviation, which form a cone with the vertex in the observer ' s eye and with the axis passing through the sun. the color sequence of the rainbow is also due to refraction. it was sir isaac newton, however, 30 years after descartes, who discovered that white light was made up of different wavelengths. red light, with the longest wavelength, bends the least, while violet, being the shortest wavelength, bends the most. the vertical angle above the horizon will be a little less than 41° for the violet ( about 40° ) and a little more for the red ( about 42° ). the secondary rainbow has an angular radius of about 50° and its color sequence is reversed from the primary. it is universally accepted that there are seven rainbow colors, which appear in the order : red, orange, yellow, green, blue, indigo, and violet. however, the


students engage in several online simulations and in - class investigations related to the density of liquids, solids, and gases. they apply new understanding about density to the design and construction of hot air balloons. they make informed predictions about the variables that may affect the launch of their homemade hot air balloons and test them. the finale is the “ got gas? ” rally where students display their balloons and use multimedia presentations to demonstrate the principles of density used in the construction of their hot air balloons. view how a variety of student - centered assessments are used in the density : got gas? unit plan. these assessments help students and teachers set goals ; monitor student progress ; provide feedback ; assess thinking, processes, performances, and products ; and reflect on learning throughout the learning cycle. present the essential question, how is science applied in the real world? hold a general discussion on this question. discuss properties of matter, such as color, shape, flexibility, strength, and as many other properties that students can brainstorm and why the properties might be important. tell students that for the next few weeks, they will be investigating the property of density. have them write everything they know about density and why density might be important. have students investigate specific properties of matter with the layered liquids lab. in this lab, students layer mystery liquids and compare their relative densities. give each team one set of equipment ( see materials on the lab worksheet ). the liquids are as follows : each group should have 5 ml of each unknown liquid. directions for the students are given in the " procedure " section on the lab sheet. ( note that this procedure can also be done as a teacher - only demonstration. ) explain that students will move from comparing the density of liquids to investigating the density of solids. have students navigate to density *, an online simulation that encourages students to experiment with different variables and determine the effects of mass and volume on density. a teacher ’ s guide and related materials are included on the site. for extended learning, students can complete the buoyancy lab *, an online simulation that helps students further explore density properties by adjusting the density of a liquid to determine the effects on buoyancy of a solid object. related handouts and materials are included on the site. through these online simulations, students should make a connection between the layered liquids lab and the online density labs. after the labs, discuss the content question, what are the relationships among mass, volume, and density? expand on the investigations from the online density labs by discussing operational definitions and how to calculate


connection between the layered liquids lab and the online density labs. after the labs, discuss the content question, what are the relationships among mass, volume, and density? expand on the investigations from the online density labs by discussing operational definitions and how to calculate density using the how dense? lab. explain to students that they will measure the absolute densities of liquids from the layered liquids lab. note that the liquids are the same as those compared in the layering liquids lab. each group ' s lab setup requires 25 ml of each sample liquid. discuss procedures and data collection in advance of the activity. explain to students that a bar graph would be appropriate for this type of data. also, this would be a good opportunity to use a spreadsheet program to input the data and make various types of graphs. this would allow students to quickly see which types of graphs are most revealing and useful. for further investigation, students can navigate to determination of density of a solid *, an online labs simulation that allows students to determine the density of various solids by using a virtual spring balance and a measuring cylinder. before beginning, ask students what they learned about comparing the density of fluids that might help them think about measuring the density of a solid. ( mass is determined by comparing an object of unknown mass to an object of known mass, using a balance scale. ) you may wish to review the lab animation * and answer any questions before students enter the simulator. after completing the simulation, have students complete the online quiz * to check for understanding. if you have limited internet access or computing equipment, you can use the optional solids lab procedure instead. following the procedures outlined in the document, students should be able to find the density of a variety of objects using the appropriate method by the end of this session. note that students will need two cubes made from different materials ( for example, steel and aluminum ) and an irregular sample of either steel or aluminum to complete this lab. ask students, if you put hot and cold water together, what will happen? discuss predictions and then do the following hot / cold density demonstration : ask students what the explanation might be for what was observed. have students write or discuss what ways temperature affects density. use online simulations to demonstrate what happens to gas molecules under different temperatures. some recommended simulations include : discuss scientific modeling and explain how molecules have been modeled in different ways over time. discuss the density of gases as compared to solids and liquids. applying density concepts to hot air balloons students are now ready to apply their knowledge about density in the construction of


: discuss scientific modeling and explain how molecules have been modeled in different ways over time. discuss the density of gases as compared to solids and liquids. applying density concepts to hot air balloons students are now ready to apply their knowledge about density in the construction of a hot air balloon. present the unit questions : how does the density of specific matter affect the construction process? and what principles of density are applied in hot air balloons? divide students into small groups. announce that the class will be hosting the “ got gas ”? hot air balloon rally. the students ’ task is to construct hot air balloons that will give riders the smoothest and longest flight. the students will work in groups and research how hot air balloons work and which variables to consider when constructing balloons. guide this activity with the balloon research worksheet. have groups create a balloon name and list as many variables that affect flight time as they can. discuss these variables as a class, and have students expand and modify notes accordingly. give each student an experiment data sheet, and present the problem, what causes some hot air balloons to have longer flight times than others? instruct students to discuss this within their groups, and write hypothesis and prediction statements. ( help narrow the choices of independent variables to those relating to balloon weight, temperature difference inside and outside the balloon, wind speed, and direction. ) have each group make a chart showing independent, dependent, and constant variables. instruct students to research the materials needed to build their balloons using the internet sources listed. students should consider the density of each of their chosen materials ( such as straws, plastic sheeting, string, paper cups, and so forth ) and provide a rationale for their choices. have groups turn in a list of supplies needed to build their balloon and have those supplies ready by the next class or have students bring in their own supplies. a pattern of a hot air balloon is included as an example, or each group can find or make their own pattern. students are now ready for construction day. explain that groups should document the density of each type of material used in their hot air balloon and the rationale for choosing the material. they should also describe how they used principles of density to ensure a long flight time and smooth ride. hold the “ got gas? ” hot air balloon rally! assign each group a designated flight time. flight is judged by time, integrity of materials, and smoothness of ride. tell students to set up a data table and graph while waiting for flight times, and work on their presentations by drawing


balloon rally! assign each group a designated flight time. flight is judged by time, integrity of materials, and smoothness of ride. tell students to set up a data table and graph while waiting for flight times, and work on their presentations by drawing illustrations of their project to scan into later publications and / or taking pictures. students can also use photo editing software or online drawing programs to create high - quality visual representations of their project. share the student example slideshow and discuss the criteria for the presentations. introduce the presentation rubric and keeping track brochure checklist. explain that students are to complete two presentation projects : have groups present their multimedia presentations and display their brochures. have students self - and peer - assess their collaboration skills using the peer rubric and their presentations using the presentation rubric. note : in addition to the student brochure and slideshow presentations, students may develop a class wiki * on the topic of density. students use the density test practice to review the concepts of the density lessons and prepare for the short - answer and practical exam. present the essential question again, how is science applied in the real world? use density as the focus this time. encourage students to further investigate this question by researching other examples when knowing the density of matter is applied to other situations ( such as density of gold to identify fool ’ s gold, packaging material, body density, all construction projects, and so forth ). english language learner gina aldridge participated in the intel® teach program, which resulted in this idea for a classroom project. a team of teachers expanded the plan into the example you see here. grade level : 6 - 9 subject ( s ) : physical science topics : properties of matter higher - order thinking skills : analysis, experimental inquiry key learnings : density, scientific method time needed : 4 weeks, 50 - minute lessons, daily background : from the classroom in mesa, arizona, united states


fri january 18, 2013 inventors design lamp powered entirely by gravity flora lichtman, host : this is science friday. i ' m flora lichtman, filling in for ira flatow today. solar wind, geothermal - now there ' s a new renewable energy source to add to that list. it ' s free, completely reliable and totally unlimited : the force of gravity. two british designers have invented a lamp that runs on gravity alone. their gravitylight - yes, that ' s its name, aptly named - uses, you guessed it, the pull of gravity on a weight to generate up to 30 minutes of light. to turn the lamp on, you lift a weighted bag up, and voila, as the bag slowly descends, led illumination. so how does this work? how hard is it to make? my next guest is here to tell us. martin riddiford is one of the inventors of the gravitylight and founder of the design company therefore. he joins me by phone from london, england. welcome to the program. martin riddiford : hi, flora. lichtman : hi. tell us what this gravitylight looks like, and then take us under the hood and tell us how it works. riddiford : ok. so gravitylight is a project which we started, because we were working with a charity trying to find an alternative to kerosene lamps for the developing world. and we were working with solar power at the time, and we were doing a lamp which used led bulbs and a battery. and we - you had to charge it through solar panels. and we found out that the cost of the unit was too expensive for people in africa to buy, because they have very, very limited finances. and there ' s no micro - financing in africa. so the lowest possible bum ( ph ) cost, or purchase cost, was absolutely essential in the project. so we came out of a meeting when we presented our - the latest work we ' d done with the battery powered device, and thought, we ' ve got to find a cheaper way of doing this. lichtman : now, how did you come up with the idea of - how did gravity come to mind? riddiford : well, we realized that there were two components, the led and the battery, and, obviously, the means of charging it. and there are various means of charging devices like this, with hand cranks and things like that. but they generally always involve a battery, and


joined : 16 mar 2004 | posted : tue aug 25, 2009 12 : 33 pm post subject : nanoparticles go bob bob bobbin ’ | nanoparticles go bob bob bobbin ’, create controllable surface patterns in a finding that could speed the use of sensors or barcodes at the nanoscale, north carolina state university engineers have shown that certain types of tiny organic particles, when heated to the proper temperature, bob to the surface of a layer of a thin polymer film and then can reversibly recede below the surface when heated a second time. selectively bringing a number of particles to a surface and then sinking them back below it results in controllable surface patterns. according to nc state researchers involved in the project, patterning surfaces is one of the holy grails of current nanotechnology research, and is difficult to do with certain particles. they add that the finding could result in tiny reusable bar codes, or in small fluorescent features that turn off when they sense too much heat or the presence of a certain chemical. dr. jan genzer, professor of chemical and biomolecular engineering, and dr. richard spontak, professor of chemical and biomolecular engineering and materials science and engineering, published their finding along with graduate students arif gozen and bin wei in the journal nano letters. they worked with engineers who designed the unique particles at the university of melbourne in australia. the researchers used a special type of organic nanoparticle called a core - shell microgel in which the core of a cross - linked, or networked, polymer is surrounded by a shell of a different polymer. " most polymers are chain - like macromolecules that are like very long, cooked spaghetti noodles, but these special core - shell particles are shaped more like squash balls of one polymer with a fuzzy surface of a different polymer, " spontak says. heating these approximately 30 - nanometer particles – which are hundreds of times smaller than a human hair – allows them to break through a polymer / polymer interface like a submarine coming to the surface of water. reheating the particles at a polymer surface sinks them back below the surface. " this technique allows us to place the particles right where we want them – on the surface of a thin film, " genzer says. " it can be used to create a reusable bar code, for instance, or other functional polymer surfaces. "


the following html text is provided to enhance online readability. many aspects of typography translate only awkwardly to html. please use the page image as the authoritative form to ensure accuracy. polymer science and engineering : the shifting research frontiers stability in air at 240°c to permit blending and processing with conventional polymers. the oxidative and hydrolytic stability is significantly increased when the conducting polymer is used in the form of blends with conventional polymers. clearly, research to improve the stability of conducting polymers is essential to commercial applications in the future. polyaniline is currently the leading conducting polymer used in technological applications and is commercially available in quantity. polypyrrole and derivatives of polythiophene and poly ( phenylene vinylene ) also have significant potential technological applications. rechargeable polyaniline batteries and high - capacity polypyrrole capacitors are in commercial production. ironically conducting polymers are now being used in batteries and electrochromic displays. however, even though conductivities of greater than 10 - 3 s / cm are now achievable with gel electrolytes, the goal of preparing single - ion ( and specifically cation ) conductors with comparable conductivities has remained elusive. tight ion pairing between li + and polymer - bound anions ( usually sulfonates ) is responsible for the significantly lower conductivities. also, new approaches for the synthesis of polymer electrolytes as thin films directly on electrodes ( via, for example, photopolymerization ) are needed to complement novel multilayer battery fabrication technology. along these lines, a key goal is the design of multifunctional polymers capable of transporting only cations, stabilizing a battery system against overcharging, and exhibiting low reactivity at alkali metal and metal oxide electrodes. perhaps most important, electrode - polymer electrolyte reactions need to be examined from a fundamental point of view because these represent a major problem for battery cyclability and overall stability. the field of sensors is diverse, reflecting our need to control increasingly complex systems — including environments, processes, equipment, vehicles, and biomedical procedures — that are characterized by high levels of automation. the key to the success of such automated systems is the measurement technology, which demands rapid, reliable, quantitative measurement of the required control parameters. these parameters include temperature, pressure, humidity, radiation, electric charge or potential, light, shock and acoustic waves, and the concentrations of specific chemicals in any environment, to name just a few. obviously,


the university of illinois at urbana - champaign have devised a dynamic and reversible way to assemble nanoscale structures and have used it to encrypt a morse code message. the team started with a template of dna origami ― multiple strands of dna woven into a tile. they “ wrote ” their message in the dna template by attaching biotin - bound dna strands to specific locations on the tiles that would light up as dots or dashes. scientists in australia are perfecting a technique that may help see nanodiamonds used in biomedical applications. they have been processing the raw diamonds so that they might be used as a tag for biological molecules and as a probe for single - molecule interactions. with the help of an international team, these diamonds have recently been optically trapped and manipulated in three dimensions — the first time this has been achieved. in systemic lupus erythematosus, the body attacks itself for largely mysterious reasons, leading to serious tissue inflammation and organ damage. current drug treatments address symptoms only and can require life - long daily use at toxic doses. now, scientists at yale university have designed and tested a drug delivery system that uses biodegradable nanoparticles to deliver low drug doses. the method shows early promise for improved treatment of lupus and other chronic, uncured autoimmune diseases. a new study has examined how bacteria clog medical devices, and the result isn ’ t pretty. the microbes join to create slimey ribbons that tangle and trap other passing bacteria, creating a full blockage in a startlingly short period of time. the finding could help shape strategies for preventing clogging of devices such as stents and water filters many researchers have been investigating the potential of tiny particles filled with drugs to treat cancer. a team of scientists in sweden have recently made an advance in this area of research by developing “ theranostic ” nanoparticles, which combine therapy and diagnostics in the same nanomaterial. they are trackable through magnetic resonance. just like electronics, living cells use electrons for energy and information transfer. but cell membranes have thus far prevented us from “ plugging ” in cells to our computers. to get around this barrier that tightly controls charge balance, a research group at lawrence berkeley national laboratory ’ s molecular foundry has engineered < em > e. coli < / em > as a testbed for cellular - electrode communication. they have now demonstrated that these bacterial strains can generate measurable current at an anode. a new study provides details of the


s molecular foundry has engineered < em > e. coli < / em > as a testbed for cellular - electrode communication. they have now demonstrated that these bacterial strains can generate measurable current at an anode. a new study provides details of the structure and tissue properties of the remora fish ' s unique adhesion system. the researchers plan to use this information to create an engineered reversible adhesive inspired by the remora that could be used to create pain - and residue - free bandages, attach sensors to objects in aquatic or military reconnaissance environments, replace surgical clamps, and help robots climb. researchers from north carolina state university have, for the first time, successfully coated polymer implants with a bioactive film. the discovery should improve the success rate of such implants. the polymer used in these implants, called peek, does not bond well with bone or other tissues in the body. this can result in the implant rubbing against surrounding tissues, which can lead to medical complications and the need for additional surgeries. biomembranes consist of a mosaic of individual, densely packed lipid molecules. these molecules are formed inside the cells. but how do these building blocks move to the correct part of the membrane? researchers in germany have discovered the bilayer structural mechanism that demonstrates how this is done. a team of materials scientists at harvard university and the university of exeter have invented a new fiber that changes color when stretched. inspired by nature, the researchers identified and replicated the unique structural elements that create the bright iridescent blue color of a tropical plant ' s fruit. researchers in switzerland have designed tiny vessels that are capable of releasing active agents in the body. these “ nanovehicles ” are made from a liposome just 100 to 200 nm in diameter. by attaching magnetic iron oxide nanoparticles to the surface, scientists are able to target the vessel, heating it up to release the drug. scientists at arizona state university are celebrating their recent success on the path to understanding what makes the fiber that spiders spin — weight for weight — at least five times as strong as piano wire. they have found a way to obtain a wide variety of elastic properties of the silk of several intact spiders ' webs using a sophisticated but non – invasive laser light scattering technique. a university of british columbia researcher has helped create a gel — based on the mussel ' s knack for clinging to rocks, piers, and boat hulls - that can be painted onto the walls of blood vessels and stay put, forming a protective