Question: Which material best conducts heat and electricity?

Choices:
A. rubber
B. metal
C. plastic
D. wood


Question: Which two characteristics affect a planet's gravitational attraction to the Sun?

Choices:
A. length of day and distance from the Sun
B. volume and length of day
C. mass and volume
D. distance from the Sun and mass

local Hugging Face dataset card: ai2_arc/README.md


Question: When a prairie ecosystem was disturbed, an invasive grass species outcompeted the native grass. The new grass had less nutritional value for the organisms living in the area. Which category of organism will be affected by this change first?

Choices:
A. herbivores
B. scavengers
C. predators
D. decomposers


Question: In the 1970s, the pesticide DDT was used to kill insects that damaged fruit and vegetable crops. Most insects died from being exposed to DDT, but some survived. These surviving insects contributed to an increase in their population by

Choices:
A. migrating to habitats that had different types of crops.
B. learning how to avoid being exposed to DDT.
C. competing with other types of insects for food.
D. passing the gene for DDT resistance to their offspring.

passing the gene for DDT resistance to their offspring.


Question: Binary stars orbit around the center of mass of the two stars. What causes the stars to remain together?

Choices:
A. energy released from the stars
B. nuclear reactions in the stars
C. magnetic attraction between the stars
D. gravity between the stars


Question: After a star runs out of most of its hydrogen fuel, it becomes hotter and more luminous. What stage does this represent in the life cycle of a star?

Choices:
A. red giant
B. protostar
C. white dwarf
D. quasar


Question: How does no-till farming help the environment?

Choices:
A. It decreases soil erosion.
B. It increases fertilizer use.
C. It increases soil removal.
D. It decreases crop yield.


Question: In a laboratory, a sealed container with 100 g of steam is cooled until all the steam becomes a liquid. The container is then cooled further until all the water becomes a solid. Which of the following remains constant during both of these changes?

Choices:
A. the pressure in the container
B. the mass of the water
C. the total energy of the water
D. the position of the atoms in the container


Question: A student has decided to investigate whether the number of flowers on a plant will increase if the water supply to the plant is increased. She has five pots of geranium plants to use in her experiment. What factor in the experiment should be varied for the five plants in order to answer the student's question?

Choices:
A. age of seedlings
B. volume of water
C. temperature of water
D. number of hours in sunlight


Question: The energy that allows the water cycle to occur comes from

Choices:
A. radioactive decay.
B. electricity.
C. friction.
D. the Sun.


Question: Organisms that are classified as multicellular must have

Choices:
A. identical cells.
B. more than one cell.
C. only one cell.
D. large cells.


Question: Where does air go when a person breathes in?

Choices:
A. Into the stomach
B. Into the heart
C. Into the lungs
D. Into the liver


Question: Kudzu vines grow by climbing and wrapping around trees. Trees covered by kudzu can die because they are starved of sunlight. What type of relationship exists between the trees and the kudzu growing on them?

Choices:
A. predator-prey
B. competition
C. parasitism
D. mutualism


Question: In the United States, which is responsible for ensuring the safety of the country's drinking water?

Choices:
A. Center for Disease Control (CDC)
B. National Oceanic and Atmospheric Administration (NOAA)
C. Environmental Protection Agency (EPA)
D. Food and Drug Administration (FDA)


Question: A student makes a fruit drink by stirring a powdered mix into cold water. Why is the fruit drink a solution?

Choices:
A. The student stirs the water.
B. The powder dissolves in the water.
C. The water changes color.
D. The water is the proper temperature.


Question: Which life function is the same for an amoeba as for other freshwater protists?

Choices:
A. the method used to obtain nutrients and energy
B. the method used to detect changes in their environment
C. the process used to constantly remove excess water
D. the process used to remove waste products from their cytoplasm

the process used to constantly remove excess water


Question: Proxima Centauri is the closest star to the Sun. Which units do astronomers most often use for the distance between Earth and Proxima Centauri?

Choices:
A. light years
B. meters
C. miles
D. astronomical units


Question: One positive effect of recycling aluminum cans to manufacture new beverage containers is

Choices:
A. warming Earth's atmosphere
B. creating acid rain
C. increasing the ozone layer
D. conserving Earth's resources


Question: Students are conducting an investigation to see how sunlight affects the speed of plant growth. They measure the growth of the plant at the end of two weeks. What would be the best way to communicate the results of this investigation?

Choices:
A. make a chart or graph
B. draw a picture
C. tell the science teacher
D. make some notes


Question: The conservation of matter can be demonstrated by using chemical equations. Which chemical equation demonstrates the conservation of matter?

Choices:
A. 4P + 5HNO_{3} -> 5NO + 3H_{3}PO_{4}
B. Cl + 4Na -> 4NaCl
C. 2Sn + 4HNO_{3} -> SnO_{2} + 4NO_{2} + H_{2}O
D. I_{2} + 5Cl_{2} + 6H_{2}O -> 2HIO_{3} + 10HCl


Question: As the amount of carbon dioxide in the atmosphere increases, which occurrence is most likely a long-term result?

Choices:
A. Rainforests will be unable to support animal life.
B. Volcanoes will erupt more often.
C. The number of earthquakes will decrease.
D. The polar ice caps will melt.


Question: Which mineral, found in Arkansas, is an ore that can be used to produce aluminum?

Choices:
A. quartz
B. diamond
C. bauxite
D. galena


Question: A summer day begins with a clear, sunny sky. Then, dark clouds form in the afternoon. What type of weather will MOST likely happen next?

Choices:
A. Fog and wind
B. Wind and snow
C. Sleet and snow
D. Rain and thunder


Question: Eagles have strong, sharp beaks that are most likely adapted for the eagle to eat

Choices:
A. flowers.
B. fish.
C. eggs.
D. worms.


Question: When a spoon hits a table, it makes a loud sound. When the spoon hits a soft cushion, it does not make a sound. What is the difference between the table and the cushion that accounts for the sound?

Choices:
A. The table has more potential energy than the cushion.
B. The table is more reactive than the cushion.
C. The table is more insulated than the cushion.
D. The table vibrates more than the cushion.

The table vibrates more than the cushion.


Question: When Dennis operates his lawnmower, he notices the engine makes a lot of noise. He also notices that the engine gets very hot. Which best describes the heat and noise generated from the lawnmower?

Choices:
A. thermal expansion
B. mechanical advantage
C. an increase in entropy
D. a change in phase


Question: What objects are affected by Earth's gravity?

Choices:
A. only objects that sink in water
B. only objects that are made of metal
C. only objects that have mass
D. only objects that are heavier than air


Question: Abnormal cell division in humans may result in

Choices:
A. cancer
B. dynamic equilibrium
C. asexual reproduction
D. fertilization


Question: A donkey and a horse can be bred to produce a mule. Which observation is evidence that donkeys and horses are two different species?

Choices:
A. A mule is not able to reproduce.
B. A mule does not resemble either parent.
C. They have different body sizes.
D. They are found in different environments.


Question: What should students use to identify the percent chance of a trait being passed down from a parent to its offspring?

Choices:
A. a graph
B. a data table
C. a flow chart
D. a Punnett square


Question: Which rankings of trees would most likely useful in a scientific study of fruit production in apple trees?

Choices:
A. date of flowering and the fruit yield
B. date of flowering and smell of the flower
C. taste of the fruit and smell of the flower
D. fruit yield and taste of the fruit


Question: Which of the following characteristics is an acquired trait?

Choices:
A. hair color
B. eye shape
C. language
D. height


Question: Which stimulus causes a responding plant to demonstrate phototropism?

Choices:
A. intensity of light
B. length of day
C. direction of light
D. time of day


Question: Estuaries are marine environments located in areas where fresh water from rivers flow into the ocean. Estuaries are one of the most biologically productive ecosystems. Birds, fish, turtles and many other organisms inhabit these ecosystems. Which will most likely cause changes to estuary habitats on a global scale?

Choices:
A. increases in earthquakes
B. increases in sea level
C. decreases in volcanic eruptions
D. decreases in powerful hurricanes


Question: The trunk of a pine tree supports the tree. Which part of a daisy supports the plant the same way?

Choices:
A. flower
B. stem
C. leaf
D. root


Question: What property of electromagnetic waves makes it possible to use these waves to transmit information between a space shuttle and NASA mission control centers on the ground?

Choices:
A. Electromagnetic waves are all visible to human eyes.
B. Electromagnetic waves can travel through a vacuum.
C. Electromagnetic waves are transverse waves.
D. Electromagnetic waves have very low velocity.

Electromagnetic waves can travel through a vacuum.


Question: A student is investigating solar energy by cooking food in an oven powered by the Sun. On which of the following days will the food cook most quickly?

Choices:
A. a warm, cloudy day
B. a warm, sunny day
C. a hot, cloudy day
D. a warm, rainy day


Question: Which is the correct order of the planets from the Sun?

Choices:
A. Mercury, Earth, Mars, Venus, Saturn, Jupiter, Neptune, Uranus
B. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
C. Mercury, Venus, Earth, Saturn, Uranus, Jupiter, Mars, Neptune
D. Mercury, Venus, Mars, Earth, Jupiter, Uranus, Saturn, Neptune

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune


Question: Which of these is the basic building block of complex organisms?

Choices:
A. a cell
B. an organ system
C. an organ
D. a tissue


Question: Which human response is most likely to occur because the air temperature is 90°F?

Choices:
A. salivating
B. sweating
C. shivering
D. blinking


Question: What are the properties of the Earth's crust and mantle that are most responsible for Earth's tectonic activity?

Choices:
A. They are in the same state but have different temperatures.
B. They are in different states and have different temperatures.
C. They are in different states but have the same temperature.
D. They are the same state and have the same temperature.

They are in different states and have different temperatures.


Question: When a butterfly emerges from its chrysalis, its wings are crumpled. In order to expand its wings, the butterfly hangs upside down, causing fluid to be pumped into the veins of its wings. This pumping most likely expands the wings by

Choices:
A. decreasing the mass of the wings
B. increasing the temperature inside the wings
C. decreasing the density of the wings
D. increasing the pressure inside the wings

increasing the pressure inside the wings


Question: Which of the following characteristics will best prevent a tree from being blown over by high winds during a storm?

Choices:
A. wide leaves
B. deep roots
C. thick bark
D. long branches


Question: Both prokaryotes and eukaryotes have small, free-floating organelles. The cell makes these organelles from nucleic acids and amino acids found in food. Without these organelles, the cell could not make proteins. What are these organelles called?

Choices:
A. mitochondria
B. ribosomes
C. vesicles
D. chloroplasts


Question: Which temperature is the freezing point of water?

Choices:
A. 0°F
B. 100°F
C. 32°F
D. 50°F


Question: Which statement best describes the molecules in a sample of water that was heated from a liquid to a gas?

Choices:
A. The average kinetic energy of the molecules increased.
B. The average kinetic energy of the molecules decreased.
C. The average size of the molecules increased.
D. The average size of the molecules decreased.

The average kinetic energy of the molecules increased.


Question: Constellations are patterns of objects seen in the night sky from Earth. How are the objects in constellations like the Sun?

Choices:
A. The objects are planets.
B. The objects are stars.
C. The objects heat the atmosphere of Earth.
D. The objects are located in this solar system.


Question: Which is a trait a human most directly inherits from its parents?

Choices:
A. eye color
B. career choice
C. interest in reading
D. musical taste


Question: When observing a very small piece of dust in a liquid under a microscope, the dust appears to jiggle slightly. This movement results from the dust interacting with the molecules in the liquid. What property of the molecules in the liquid causes this effect?

Choices:
A. The molecules frequently change shape.
B. The molecules transfer an electric charge to the dust particles.
C. The molecules are always in random motion.
D. The molecules briefly form chemical bonds with nearby objects.

The molecules are always in random motion.


Question: Which of the following happens in our solar system?

Choices:
A. Earth revolves around the sun once per year.
B. The moon revolves around Earth once per day.
C. The moon revolves around Earth once per year.
D. Earth revolves around the sun once per day.

Earth revolves around the sun once per year.


Question: On a cold day, a student felt the tires of her bike before riding it to the store. When she arrived at the store, she felt the tires again and noticed that they were warmer. What caused the temperature of the bicycle tires to change?

Choices:
A. the wind blowing against the tires
B. the heat transferring from the rider's hands to the tire
C. the rubbing between the ground and the tires
D. the air escaping from the spinning tires

the rubbing between the ground and the tires


Question: Chloroplasts in cells make it possible for the cells to

Choices:
A. hold their rigid shape.
B. absorb and excrete materials.
C. carry out photosynthesis.
D. reproduce.


Question: Which of these is the most important product of Virginia forests?

Choices:
A. Pine cones
B. Hardwood lumber
C. Pecan trees
D. Maple leaves


Question: Research in which of these areas has the greatest impact on the environment?

Choices:
A. bacteria to clean up oil spills
B. organic fertilizers
C. irradiating food
D. developing larger, sweeter strawberries


Question: The surface of Earth is covered mostly by

Choices:
A. molten rock
B. water
C. ice
D. solid rock


Question: Which pair of systems is responsible for the flow of blood in the human body?

Choices:
A. muscular and circulatory systems
B. respiratory and muscular systems
C. circulatory and skeletal systems
D. skeletal and excretory systems


Question: Where are the most reactive metals located on the periodic table?

Choices:
A. the second column from the right side of the table
B. the rows at the bottom of the table connecting two section
C. the uppermost complete row of the table
D. the column at the far left side of the table

the column at the far left side of the table


Question: What major and potentially catastrophic events can be predicted to occur in the Northern Hemisphere between the months of June and November?

Choices:
A. tsunamis
B. volcanic eruptions
C. hurricanes
D. asteroid impacts


Question: The pull of gravity from Earth has the greatest effect on

Choices:
A. comets.
B. asteroids.
C. the Moon.
D. the Sun.


Question: What is the main advantage of making a laptop computer light in weight?

Choices:
A. to make the screen easy to read
B. to make it easy to carry
C. to provide storage for an electrical cord
D. to keep it simple to build


Question: It takes 365 days for

Choices:
A. Earth to complete one orbit around the Sun.
B. the Moon to travel halfway around Earth.
C. the Moon to complete one orbit around Earth.
D. Earth to travel halfway around the Sun.

Earth to complete one orbit around the Sun.


Question: Some scientists once believed that Earth was solid like a marble. Which of these has been most responsible for changes in the scientific view of the structure of Earth?

Choices:
A. a physical model of Earth showing its layers
B. discussions among earth scientists about new data
C. a lead scientist explaining the structure of Earth
D. scientific books defining the layers of Earth

discussions among earth scientists about new data


Question: A student wants to organize a group of animals into two categories based on observable external features. Which display will most appropriately show the two categories of animals?

Choices:
A. a line graph
B. a pie chart
C. a data table
D. a timeline


Question: Ribosomes present in a particular cell are smaller than those found in plants. In which taxonomic group or groups could the cell be classified?

Choices:
A. bacteria or fungi
B. fungi only
C. archaea only
D. bacteria or archaea


Question: What happens to the path of a light ray as it passes from air into water at an angle?

Choices:
A. Its path becomes shorter.
B. Its path bends.
C. Its path widens.
D. Its path continues in a straight line.


Question: Vibrations in the air caused by hitting a drum form

Choices:
A. light.
B. sound.
C. radiation.
D. electricity.


Question: As humans grow, their bodies change. Which of these statements explains how humans grow?

Choices:
A. Cells undergo cell division.
B. Cells increase in size.
C. Cells form a cell wall.
D. Cells merge to become larger.


Question: Which event below involves a constructive force?

Choices:
A. flood
B. earthquake
C. wind storm
D. volcanic eruption


Question: Which of the following are formed when two crustal plates collide with one another?

Choices:
A. mid-ocean ridges
B. mountain ranges
C. hot spots
D. rift valleys


Question: The nucleus contains DNA. Which statement best describes how DNA controls the working of the cell?

Choices:
A. It codes for proteins.
B. It inhibits division of cells.
C. It regulates traffic in and out of the cell.
D. It helps in energy transformation.


Question: Which of the following provides the best evidence that Earth has evolved over geologic time?

Choices:
A. rock containing fossilized seashells found on a mountaintop
B. coral reefs that slowly changed size
C. desert sand dunes that were shaped by winds
D. deposits of sediment found at the mouth of a river

rock containing fossilized seashells found on a mountaintop


Question: The best explanation of why carnivores are dependent on plants is because they

Choices:
A. need carbon dioxide released by plants.
B. use plants for shelter.
C. need to consume plant matter.
D. consume other animals that eat plants.


Question: In the late 1600s, Anton van Leeuwenhoek began making observations with simple magnifying lenses that he constructed. To which scientific field is Leeuwenhoek credited with the most contributions?

Choices:
A. microbiology
B. plant genetics
C. DNA sequencing
D. disease control


Question: Which section of Earth is composed primarily of liquid metal?

Choices:
A. outer core
B. crust
C. mantle
D. inner core


Question: One way humans store energy is by making the molecule glycogen. Clusters of which atoms are rearranged when the body digests plant sugars to make glycogen?

Choices:
A. oxygen, sulfur, carbon
B. carbon, hydrogen, oxygen
C. hydrogen, nitrogen, carbon
D. nitrogen, carbon, sulfur


Question: The number of stars in the Milky Way Galaxy is best estimated as

Choices:
A. one hundred trillion.
B. one hundred billion.
C. one hundred million.
D. one hundred thousand.


Question: Which type of substances serves as a catalyst for reactions that break large food molecules into smaller useful molecules?

Choices:
A. vitamins
B. lipids
C. nucleotides
D. enzymes


Question: What effect does gravity always have on an object on Earth?

Choices:
A. pulls the object downward
B. makes the object move
C. makes the object stay still
D. pushes the object upward


Question: Which is the best example of a chemical reaction?

Choices:
A. a prism refracts sunlight into light of different wavelengths
B. blocked sunlight casts a shadow
C. oxygen absorbs sunlight forming ozone molecules
D. sunlight evaporates water from a lake

oxygen absorbs sunlight forming ozone molecules


Question: Some one-celled organisms can reproduce by the process of

Choices:
A. cell division
B. metamorphosis
C. hormone secretion
D. fertilization


Question: One important use of coal is to produce energy for homes. Coal can be burned and converted to

Choices:
A. electrical energy.
B. nuclear energy.
C. wind energy.
D. solar energy.


Question: Which of the following is NOT a mixture?

Choices:
A. Air
B. Salt
C. Orange juice
D. Blood


Question: What kind of energy do all moving objects have?

Choices:
A. Solar energy
B. Renewable energy
C. Kinetic energy
D. Light energy


Question: In a forest ecosystem, the squirrels eat seeds from trees. The squirrels are then eaten by hawks, owls, and foxes. If there were no more owls present in this ecosystem, which would most likely happen in the forest?

Choices:
A. The squirrel population would increase.
B. The hawk population would decrease.
C. The tree population would increase.
D. The fox population would decrease.


Question: Which of the following has the greatest direct influence on movement of the lithosphere?

Choices:
A. the Sun
B. the Moon
C. Earth's core
D. Earth's mantle


Question: When humans first began to grow crops, which of these most likely contributed to the extinction of native animal species?

Choices:
A. habitat destruction
B. pollution
C. climate change
D. tectonic plate motion


Question: Which of these does the MOST harm to the air?

Choices:
A. Cutting grass with a gas-powered lawnmower
B. Chopping down trees with an ax in the backyard
C. Collecting fall leaves
D. Picking colorful wildflowers along the highway

Cutting grass with a gas-powered lawnmower


Question: A scanning electron microscope is best suited for observing

Choices:
A. the surfaces of small objects.
B. topographical features on the ocean floor.
C. tectonic features on planets.
D. diffraction of light.


Question: A bird eats a brightly-colored insect that tastes bad. The bird avoids preying on this type of insect again. This example is best described as

Choices:
A. a learned behavior.
B. an inherited behavior.
C. a physical characteristic.
D. an adaptation.


Question: In winter, the arctic fox has white fur. In summer, its fur changes color to brown and gray. The change in fur color helps the arctic fox to ___.

Choices:
A. mate
B. hibernate
C. run
D. hide


Question: In which ways are hills most different from mountains?

Choices:
A. Hills are smaller and more rounded.
B. Hills are deeper and more level.
C. Hills are taller and snowy.
D. Hills are steeper and rockier.


Question: A bird builds a nest to

Choices:
A. produce more feathers
B. shelter its offspring
C. hibernate in winter
D. eliminate waste


Question: Which statement best describes the motion of the molecules of a solid object?

Choices:
A. They vibrate in place within a fixed volume.
B. They move around freely within a fixed volume.
C. They vibrate in place and take the shape of a container.
D. They move around freely and take the shape of a container.

They vibrate in place within a fixed volume.


Question: What happens when salt water is boiled?

Choices:
A. The water evaporates and the salt remains in the beaker.
B. Both the salt and the water evaporate and leave the beaker.
C. The salt will evaporate from the water and disperse into the environment.
D. The salt becomes a new compound.

The water evaporates and the salt remains in the beaker.


Question: Which set of elements has similar bonding properties?

Choices:
A. K, Ca, and Sc
B. Be, C, and O
C. Kr, Cl, and O
D. Cl, Br, and F


Question: Which body system processes foods into a useable source of energy?

Choices:
A. digestive
B. skeletal
C. circulatory
D. nervous


Question: What is the best way for a scientist to begin an investigation on a population of deer?

Choices:
A. observing the deer in their own habitat
B. typing results into a computer
C. writing facts in a field notebook
D. intuition


Question: Which property of an object describes how easily electricity travels through it?

Choices:
A. color
B. reflectivity
C. temperature
D. conductivity


Question: Which is a statement of fact?

Choices:
A. The Sun is fun to study.
B. The Sun is more interesting than the Moon.
C. The Sun is larger than Earth.
D. The Sun is very pretty.


Question: Sydney is learning about the sources of energy that can run out. Which energy source will run out the fastest?

Choices:
A. sunlight
B. wind
C. natural gas
D. flowing water


Question: The first organisms to occupy an area after a prairie fire are known as

Choices:
A. pioneer species.
B. succession species.
C. primary species.
D. secondary species.


Question: Which of the following is caused by a virus?

Choices:
A. tuberculosis
B. ulcer
C. malaria
D. influenza


Question: When a beam of light passes through a clear, convex lens, the light will mostly

Choices:
A. refract and spread out.
B. diffract and come to a focal point.
C. refract and come to a focal point.
D. diffract and spread out.


Question: The symptoms of strep throat infection are a red and swollen throat. What is the most likely cause of strep throat?

Choices:
A. running in cold weather
B. invading bacteria
C. drinking lemonade
D. eating raw vegetables


Question: Compared to the particles in a hardened lava sample, the particles in a liquid lava sample

Choices:
A. have a lower temperature
B. have less kinetic energy
C. are closer together
D. are moving faster


Question: Which characteristic do both the Moon and Earth share?

Choices:
A. They both have the same gravitational pull.
B. They both have rocky surfaces.
C. They both have similar atmospheres.
D. They both have active volcanoes.


Question: Which would be the most likely effect of a large decrease in the number of woodpeckers in a forest?

Choices:
A. The number of trees in the forest would increase.
B. Temperatures would increase.
C. The insect population in the forest would increase.
D. Precipitation would increase.

The insect population in the forest would increase.


Question: Which two life processes occur in both plants and humans?

Choices:
A. growing and reproducing
B. germinating and reproducing
C. growing and making food
D. germinating and making food


Question: In order for Galileo to build a telescope, he needed to know about

Choices:
A. lenses.
B. metals.
C. chemical mixtures.
D. the making of leather.


Question: A birdwatcher wants to identify an eastern bluebird. What feature of a bird should the birdwatcher evaluate first to identify an eastern bluebird?

Choices:
A. tail-feather length
B. eye position
C. beak shape
D. feather pattern


Question: When a neutral atom gains or loses electrons, it becomes

Choices:
A. less charged.
B. an ion.
C. more stable.
D. an isotope.


Question: Which is an effect of regular exercise?

Choices:
A. weaker bones
B. better hearing
C. stronger heart
D. less energy


Question: A light year is used to measure

Choices:
A. time.
B. luminosity.
C. distance.
D. temperature.


Question: As an object falls, air resistance gradually increases until it is equal with the pull of gravity. This effect is called

Choices:
A. final velocity.
B. initial velocity.
C. escape velocity.
D. terminal velocity.


Question: All of these elements are metals except

Choices:
A. aluminum.
B. helium.
C. sodium.
D. gold.


Question: Observation and measurement are important to scientific investigations because

Choices:
A. they are part of the instructions.
B. they keep you safe during an investigation.
C. they are required to make a hypothesis.
D. they are used to test a hypothesis.


Question: When air rises over the open ocean, a low pressure system is formed. Which factor increases the potential of a low pressure system developing into a hurricane in the Northern Hemisphere?

Choices:
A. cold air moving south from the North Pole
B. warm water temperatures in the tropics
C. cool ocean currents circulating towards the equator
D. increased volcanic activity in the upper latitudes


Question: Imprints of the shells of ocean clams are often found in the rocks of the Appalachian Mountains. What do these imprint fossils most likely indicate?

Choices:
A. Ocean clams evolved from mountain river clams.
B. Mountain river clams evolved from ocean clams.
C. These mountains were once under the ocean.
D. These mountains once had a more rainy climate.

These mountains were once under the ocean.


Question: A population of ground squirrels has established a community in the grasslands of the Great Plains. Temperatures often reach -15°C for most of the winter. What is the most likely behavior the ground squirrels use to survive these winter temperatures?

Choices:
A. burrowing below the frost point of the soil surface
B. consuming roots found under the soil surface
C. consuming organisms found in the soil surface
D. burrowing in tree trunks above the soil surface

burrowing below the frost point of the soil surface


Question: Which is the lowest level of environmental organization that would include the water quality and air temperature in an area?

Choices:
A. community
B. population
C. ecosystem
D. biome


Question: When you bend your arm at the elbow, the bones and muscles in your arm are acting as a system. What simple machine does this system represent?

Choices:
A. Wedge
B. Pulley
C. Lever
D. Inclined plane


Question: A student places a pan of water on the stove. What happens to some of the water as it is heated to a boil?

Choices:
A. It gets destroyed.
B. It becomes a gas.
C. It becomes a solid.
D. It gets new atomic bonds.


Question: What are the parts that make up an atom?

Choices:
A. neutrons, protons, and alpha particles
B. electrons, neutrons, and protons
C. neutrons, photons, and beta particles
D. electrons, protons, and gamma rays


Question: One end of a metal rod is placed over a flame during an investigation. A thermometer is touching the opposite end of the metal rod. Which best describes what is happening during this investigation?

Choices:
A. Heat from the flame is conducted through the metal rod to the thermometer.
B. Mechanical energy from the flame carries heat to the thermometer.
C. Convection carries heat to the thermometer.
D. Radiant energy warms the thermometer.

Heat from the flame is conducted through the metal rod to the thermometer.


Question: Mountains are most likely formed

Choices:
A. from earthquakes.
B. along tectonic plates.
C. when glaciers melt.
D. when land sinks.


Question: Read the information about Alice's science project then answer the question. Alice needed to design a science project. She decided that she wanted to focus her project on how an earthworm's behavior helps it survive. Alice wrote down four ideas about earthworm behavior that she wanted to test. Which idea can be tested experimentally?

Choices:
A. Earthworms are happier in black dirt than red dirt.
B. Earthworms exist to decompose decaying materials.
C. Earthworms will move away from direct light sources.
D. Earthworms like the taste of dirt better than sand.

Earthworms will move away from direct light sources.


Question: What do the elements sulfur (S), nitrogen (N), phosphorus (P), and bromine (Br) have in common?

Choices:
A. They are nonmetals.
B. They have the same number of protons.
C. They are noble (inert) gases.
D. They have the same thermal conductivity.


Question: Tissue plasminogen activator is a natural blood thinner. The coded sequence for the blood thinner is called PLAT , found on chromosome 8. It is used to treat people who have heart attacks and strokes. Tissue plasminogen activator can be made through genetic engineering. What is tissue plasminogen activator?

Choices:
A. a protein
B. a platelet
C. a gene
D. a DNA molecule


Question: Which of these groups contains only metric measurements?

Choices:
A. inches, grams, ounces
B. inches, pounds, ounces
C. centimeters, pounds, milliliters
D. centimeters, grams, milliliters


Question: Scientists use large optical telescopes to obtain information about the planets in the solar system. What wavelengths of electromagnetic radiation provide this information?

Choices:
A. infrared radiation
B. gamma radiation
C. radio waves
D. visible light


Question: Which scientist is credited for the development of the polio vaccine?

Choices:
A. Jonas Salk
B. Albert Einstein
C. Neil Armstrong
D. Jacques Cousteau


Question: When a volcano erupts, new lava is deposited on the slopes of the volcano. After the lava cools and hardens, which types of organisms will most likely be the first to live on the new material?

Choices:
A. small birds and mammals
B. large reptiles and amphibians
C. bushes and vines
D. mosses and lichens


Question: Ella waves good-bye from the bus. What body system pulls on bones to let Ella wave her arm?

Choices:
A. muscular system
B. nervous system
C. digestive system
D. circulatory system


Question: Coral reefs are found in shallow tropical ocean waters. A coral reef is a diverse ecosystem that is supported by the photosynthesis of marine plants and the algae that live within the tissues of the coral. Given this information, when would the waters in a coral reef likely have the highest dissolved oxygen concentration?

Choices:
A. 7 a.m.
B. midnight
C. 9 p.m.
D. 2 p.m.


Question: What keeps the planets in orbit around the Sun?

Choices:
A. magnetism
B. electricity
C. tides
D. gravity


Question: As seen from Earth, the appearance of the Moon changes throughout the month. What causes the appearance of the Moon to change?

Choices:
A. Earth revolving around the Sun
B. the Moon rotating on its axis
C. the Moon revolving around Earth
D. Earth rotating on its axis


Question: In producing an automobile, which of the 27 following is the best use of a robot?

Choices:
A. to perform quality control inspections
B. to determine the trunk space
C. to perform repetitive tasks
D. to demonstrate passenger comfort


Question: The Theory of Plate Tectonics is based on

Choices:
A. evidence of sea floor spreading.
B. an analysis of soil at the plate boundaries.
C. topographic mapping of mountain ranges.
D. volcanic activity along coastlines.


Question: Which of the following must all plant and animal species do in order for each species to survive?

Choices:
A. reproduce
B. change color
C. migrate
D. make food


Question: Which activity illustrates the main function of the motor neuron complex?

Choices:
A. delivering regular impulses to the autonomic system
B. receiving sensory impulses from the environment
C. transferring impulses to the appropriate muscle
D. processing impulses within the cerebral cortex

transferring impulses to the appropriate muscle


Question: Nutrients are recycled when materials decompose in an ecosystem. Which is the best example of the decomposition process where organic material is recycled in an ecosystem?

Choices:
A. a hawk eating a mouse
B. worms tunneling through soil
C. a plant using nitrogen to make proteins
D. bacteria feeding on dead plants


Question: What is one function of tree roots?

Choices:
A. to absorb water
B. to absorb sunlight
C. to make food
D. to make seeds


Question: Food contains stored chemical energy. Which units of measurement can be used to compare the amounts of energy in different foods?

Choices:
A. newtons
B. calories
C. decibels
D. watts


Question: The freezing and expanding of water in the cracks of rocks is a form of

Choices:
A. weathering.
B. deposition.
C. faulting.
D. erosion.


Question: Which of the following is a way that everyone can help with conservation efforts?

Choices:
A. visit a landfill
B. camp in the woods
C. use disposable plates
D. use biodegradable materials


Question: Historically, how has the compass been used?

Choices:
A. to predict weather
B. to measure temperature
C. for mineral identification
D. for navigation


Question: A cut to the skin is treated with antiseptic first to avoid

Choices:
A. a bacterial infection.
B. an allergic reaction.
C. bruising of tissues.
D. an immune response.


Question: Which would be a safe practice to exercise during laboratory investigations?

Choices:
A. removing your safety glasses when moving from station to station
B. keeping your cell phone on the laboratory countertop
C. knowing where your instructor/laboratory leader is at all times
D. using open flames to heat all materials

knowing where your instructor/laboratory leader is at all times


Question: The shape of the moon appears to change regularly during each month. Which of the following best explains why the shape of the moon appears to change?

Choices:
A. The Moon orbits around the Earth.
B. The Moon turns on its axis.
C. Clouds cover the Moon.
D. The Earth turns on its axis.


Question: How do the nutrients necessary for plant growth get into the soil?

Choices:
A. Water filters through the soil.
B. Organic matter is decayed in the soil.
C. The soil absorbs sunlight.
D. The soil is exposed to air.


Question: Which part of a sunflower plant absorbs water and nutrients?

Choices:
A. Leaves
B. Stems
C. Flowers
D. Roots


Question:
What do these two changes have in common?
compost rotting
a piece of apple turning brown

Choices:
A. Both are chemical changes.
B. Both are caused by cooling.
C. Both are caused by heating.
D. Both are only physical changes.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Compost forms from the remains of plants and animals, such as vegetable scraps and egg shells. Compost rotting is a chemical change. As the compost rots, it breaks down and turns into a different type of matter.
A piece of apple turning brown is a chemical change. The apple reacts with oxygen in the air and turns into a different type of matter.
If you scrape off the brown layer of the apple, the inside is still white. The inside hasn't touched the air. So the chemical change didn't happen to that part of the apple.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science

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Question: What is the expected ratio of offspring with a woolly fleece to offspring with a hairy fleece? Choose the most likely ratio.

Choices:
A. 3:1
B. 0:4
C. 2:2
D. 1:3
E. 4:0

This passage describes the fleece type trait in sheep:
The fleece, or outer coat, of a sheep is often cut off and used to make yarn for fabrics and other textiles. Woolly fleeces, which have shorter hairs, are usually used for clothing and blankets. Hairy fleeces, which have longer hairs, are usually used for carpets.
In a group of sheep, some individuals have a hairy fleece and others have a woolly fleece. In this group, the gene for the fleece type trait has two alleles. The allele for a hairy fleece (F) is dominant over the allele for a woolly fleece (f).
This Punnett square shows a cross between two sheep.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

To determine how many boxes in the Punnett square represent offspring with a woolly fleece or a hairy fleece, consider whether each phenotype is the dominant or recessive allele's version of the fleece type trait. The question tells you that the F allele, which is for a hairy fleece, is dominant over the f allele, which is for a woolly fleece.
A woolly fleece is the recessive allele's version of the fleece type trait. A sheep with the recessive version of the fleece type trait must have only recessive alleles for the fleece type gene. So, offspring with a woolly fleece must have the genotype ff.
All 4 boxes in the Punnett square have the genotype ff.
A hairy fleece is the dominant allele's version of the fleece type trait. A sheep with the dominant version of the fleece type trait must have at least one dominant allele for the fleece type gene. So, offspring with a hairy fleece must have the genotype FF or Ff.
There are 0 boxes in the Punnett square with the genotype FF or Ff.
So, the expected ratio of offspring with a woolly fleece to offspring with a hairy fleece is 4:0. This means that, based on the Punnett square, this cross will always produce offspring with a woolly fleece. This cross is expected to never produce offspring with a hairy fleece.

natural science

Use Punnett squares to calculate ratios of offspring types


Question:
What do these two changes have in common?
butter melting on a hot day
mixing sand and water

Choices:
A. Both are caused by heating.
B. Both are chemical changes.
C. Both are only physical changes.
D. Both are caused by cooling.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Butter melting on a hot day is a change of state. So, it is a physical change. The butter changes from solid to liquid, but it is still made of the same type of matter.
Mixing sand and water is a physical change. Adding water makes the sand wet. But both the sand and water are still made of the same type of matter as before.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Butter melting on a hot day is caused by heating. But mixing sand and water is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the reptile.

Choices:
A. eastern newt
B. California toad
C. grass frog
D. Chinese alligator

Reptiles have scaly, waterproof skin. Most reptiles live on land.

A Chinese alligator is a reptile. It has scaly, waterproof skin.
Alligators live in and around water. They can live near ponds, rivers, marshes, and lakes.
An eastern newt is an amphibian. It has moist skin and begins its life in water.
Some newts live in water. Other newts live on land but lay their eggs in water.
A grass frog is an amphibian. It has moist skin and begins its life in water.
Frogs live near water or in damp places. Most frogs lay their eggs in water.
A California toad is an amphibian. It has moist skin and begins its life in water.
Toads do not have teeth! They swallow their food whole.

natural science

Identify mammals, birds, fish, reptiles, and amphibians


Question: How long is a hiking trail?

Choices:
A. 4 meters
B. 4 kilometers
C. 4 millimeters
D. 4 centimeters

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using metric units, length can be written with units of millimeters, centimeters, meters, or kilometers. One meter contains 100 centimeters or 1,000 millimeters. So, 1 meter is larger than 1 centimeter, and 1 centimeter is larger than 1 millimeter.
The tip of the pencil shown here is only 1 millimeter wide, but the pencil is about 16 centimeters long.
A red fox is about 1 meter long. The Sydney Harbour Bridge in Australia is about 1,000 meters, or 1 kilometer, in length.

The best estimate for the length of a hiking trail is 4 kilometers.
4 millimeters, 4 centimeters, and 4 meters are all too short.

natural science

Choose metric units of distance, mass, and volume


Question: What is the expected ratio of offspring with smooth fruit to offspring with fuzzy fruit? Choose the most likely ratio.

Choices:
A. 4:0
B. 2:2
C. 0:4
D. 1:3
E. 3:1

In a group of tomato plants, some individuals have smooth fruit and others have fuzzy fruit. In this group, the gene for the fruit texture trait has two alleles. The allele for smooth fruit (F) is dominant over the allele for fuzzy fruit (f).
This Punnett square shows a cross between two tomato plants.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

To determine how many boxes in the Punnett square represent offspring with smooth fruit or fuzzy fruit, consider whether each phenotype is the dominant or recessive allele's version of the fruit texture trait. The question tells you that the F allele, which is for smooth fruit, is dominant over the f allele, which is for fuzzy fruit.
Smooth fruit is the dominant allele's version of the fruit texture trait. A tomato plant with the dominant version of the fruit texture trait must have at least one dominant allele for the fruit texture gene. So, offspring with smooth fruit must have the genotype FF or Ff.
All 4 boxes in the Punnett square have the genotype FF or Ff.
Fuzzy fruit is the recessive allele's version of the fruit texture trait. A tomato plant with the recessive version of the fruit texture trait must have only recessive alleles for the fruit texture gene. So, offspring with fuzzy fruit must have the genotype ff.
There are 0 boxes in the Punnett square with the genotype ff.
So, the expected ratio of offspring with smooth fruit to offspring with fuzzy fruit is 4:0. This means that, based on the Punnett square, this cross will always produce offspring with smooth fruit. This cross is expected to never produce offspring with fuzzy fruit.

natural science


Question:
What do these two changes have in common?
dry ice sublimating and becoming a gas
burning a marshmallow over a campfire

Choices:
A. Both are caused by heating.
B. Both are chemical changes.
C. Both are only physical changes.
D. Both are caused by cooling.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Dry ice is solid carbon dioxide. When dry ice gets warm, it changes state and becomes carbon dioxide gas. This change of state, from solid to gas, is called sublimation.
Dry ice becoming a gas is a physical change. A change of state does not form a different type of matter.
Burning a marshmallow is a chemical change. The heat from the fire causes the type of matter in the marshmallow to change. The marshmallow becomes black and crispy.
Step 2: Look at each answer choice.
Both are only physical changes.
Dry ice sublimating is a physical change. But burning a marshmallow is not.
Both are chemical changes.
Burning a marshmallow is a chemical change. But dry ice sublimating is not.
Both are caused by heating.
Both changes are caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the vertebrate.

Choices:
A. comet moth
B. chinchilla
C. red-kneed tarantula
D. bull ant

Hint: Mammals, birds, fish, reptiles, and amphibians are vertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

Like other tarantulas, a red-kneed tarantula is an invertebrate. It does not have a backbone. It has an exoskeleton.
A bull ant is an insect. Like other insects, a bull ant is an invertebrate. It does not have a backbone. It has an exoskeleton.
A chinchilla is a mammal. Like other mammals, a chinchilla is a vertebrate. It has a backbone.
A comet moth is an insect. Like other insects, a comet moth is an invertebrate. It does not have a backbone. It has an exoskeleton.

natural science


Question: What is the probability that an American curl cat produced by this cross will be homozygous dominant for the ear type gene?

Choices:
A. 1/4
B. 3/4
C. 4/4
D. 0/4
E. 2/4

In a group of American curl cats, some individuals have curled ears and others have straight ears. In this group, the gene for the ear type trait has two alleles. The allele for curled ears (E) is dominant over the allele for straight ears (e).
This Punnett square shows a cross between two American curl cats.

Offspring genotypes: homozygous or heterozygous?
How do you determine whether an organism is homozygous or heterozygous for a gene? Look at the alleles in the organism's genotype for that gene.
An organism with two identical alleles for a gene is homozygous for that gene.
If both alleles are dominant, the organism is homozygous dominant for the gene.
If both alleles are recessive, the organism is homozygous recessive for the gene.
An organism with two different alleles for a gene is heterozygous for that gene.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype.
Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4

natural science

Use Punnett squares to calculate probabilities of offspring types


Question: Which of these organisms contains matter that was once part of the lichen?

Choices:
A. mushroom
B. short-tailed weasel
C. brown lemming
D. rough-legged hawk
E. bilberry

Below is a food web from a tundra ecosystem in Nunavut, a territory in Northern Canada.
A food web models how the matter eaten by organisms moves through an ecosystem. The arrows in a food web represent how matter moves between organisms in an ecosystem.

A food web is a model.
A food web shows where organisms in an ecosystem get their food. Models can make things in nature easier to understand because models can represent complex things in a simpler way. If a food web showed every organism in an ecosystem, the food web would be hard to understand. So, each food web shows how some organisms in an ecosystem can get their food.
Arrows show how matter moves.
A food web has arrows that point from one organism to another. Each arrow shows the direction that matter moves when one organism eats another organism. An arrow starts from the organism that is eaten. The arrow points to the organism that is doing the eating.
An organism in a food web can have more than one arrow pointing from it. This shows that the organism is eaten by more than one other organism in the food web.
An organism in a food web can also have more than one arrow pointing to it. This shows that the organism eats more than one other organism in the food web.

Use the arrows to follow how matter moves through this food web. For each answer choice, try to find a path of arrows that starts from the lichen.
The bilberry does not have any arrows pointing to it. So, in this food web, matter does not move from the lichen to the bilberry.There are two paths matter can take from the lichen to the mushroom: lichen->barren-ground caribou->mushroom. lichen->barren-ground caribou->grizzly bear->mushroom. brown lemming. The brown lemming has two arrows pointing to it. These arrows start from the bear sedge and the bilberry. Neither the bear sedge nor the bilberry has any arrows pointing to it. So, in this food web, matter does not move from the lichen to the brown lemming.. short-tailed weasel. The only arrow pointing to the short-tailed weasel starts from the brown lemming. The brown lemming has two arrows pointing to it. These arrows start from the bear sedge and the bilberry. Neither the bear sedge nor the bilberry has any arrows pointing to it. So, in this food web, matter does not move from the lichen to the short-tailed weasel.. rough-legged hawk. The only arrow pointing to the rough-legged hawk starts from the parasitic jaeger. The only arrow pointing to the parasitic jaeger starts from the brown lemming. The brown lemming has two arrows pointing to it. These arrows start from the bear sedge and the bilberry. Neither the bear sedge nor the bilberry has any arrows pointing to it. So, in this food web, matter does not move from the lichen to the rough-legged hawk..

natural science


Question:
What do these two changes have in common?
a slice of banana turning brown
chicken cooking in an oven

Choices:
A. Both are chemical changes.
B. Both are caused by heating.
C. Both are only physical changes.
D. Both are caused by cooling.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
A slice of banana turning brown is a chemical change. The part of the banana in contact with the air reacts with oxygen and turns into a different type of matter.
Cooking chicken is a chemical change. The heat causes the matter in the chicken to change. Cooked chicken and raw chicken are different types of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Cooking is caused by heating. But a slice of banana turning brown is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the plant.

Choices:
A. Ivy has star-shaped leaves.
B. Hippopotamuses eat plants.
C. Water buffalo eat plants.
D. Alligators eat animals.

Plants and animals are living things. Living things are called organisms.
Plants come in many shapes and sizes. Most plants grow in the ground. They might grow leaves, flowers, and fruit. Plants cannot move around on their own like animals can.
Animals also come in many shapes and sizes. Most animals can move around. Animals might run, swim, jump, or fly. Animals eat plants or other organisms for food.

An alligator is an animal. It eats other animals.
Alligators can live in ponds, rivers, marshes, and lakes.
A hippopotamus is an animal. It eats plants.
Hippopotamuses keep cool by lying in mud or water.
Ivy is a plant. It has green star-shaped leaves.
Ivy is a climbing plant. It can grow up the sides of walls, trees, and rocks. But its roots grow in the ground.
A water buffalo is an animal. It eats plants.
Water buffalo live near water. They can live near rivers or swamps.

natural science


Question: Select the vertebrate.

Choices:
A. trapdoor spider
B. forest scorpion
C. birdwing butterfly
D. wombat

Hint: Mammals, birds, fish, reptiles, and amphibians are vertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

Like other spiders, a trapdoor spider is an invertebrate. It does not have a backbone. It has an exoskeleton.
A birdwing butterfly is an insect. Like other insects, a birdwing butterfly is an invertebrate. It does not have a backbone. It has an exoskeleton.
Like other scorpions, a forest scorpion is an invertebrate. It does not have a backbone. It has an exoskeleton.
A wombat is a mammal. Like other mammals, a wombat is a vertebrate. It has a backbone.

natural science


Question:
What do these two changes have in common?
a piece of pizza rotting in a trashcan
burning a candle

Choices:
A. Both are caused by heating.
B. Both are only physical changes.
C. Both are caused by cooling.
D. Both are chemical changes.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
A piece of pizza rotting is a chemical change. The matter in the pizza breaks down and slowly turns into a different type of matter.
Burning a candle is a chemical change. Both the wick and the melted wax burn. They react with oxygen in the air and turn into soot, carbon dioxide, and water.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Burning is caused by heating. But a piece of pizza rotting is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the reptile.

Choices:
A. western gorilla
B. American alligator
C. olive toad
D. great white shark

Reptiles have scaly, waterproof skin. Most reptiles live on land.

An olive toad is an amphibian. It has moist skin and begins its life in water.
Toads do not have teeth! They swallow their food whole.
A great white shark is a fish. It lives underwater. It has fins, not limbs.
Great white sharks can live for up to 70 years.
A western gorilla is a mammal. It has fur and feeds its young milk.
Gorillas live in groups called troops. The largest male in the troop is usually the leader.
An American alligator is a reptile. It has scaly, waterproof skin.
Alligators live in and around water. They can live near ponds, rivers, marshes, and lakes.

natural science


Question: Which organ takes in oxygen from the air?

Choices:
A. brain
B. skeleton
C. lungs
D. heart

natural science


Question:
What do these two changes have in common?
baking cookies
water evaporating from a puddle

Choices:
A. Both are caused by heating.
B. Both are caused by cooling.
C. Both are chemical changes.
D. Both are only physical changes.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Baking cookies is a chemical change. Cookies are made from cookie dough. Baking turns the cookie dough into cookies. The cookies are a different type of matter than the dough.
Water evaporating from a puddle is a change of state. So, it is a physical change. The liquid changes into a gas, but a different type of matter is not formed.
Step 2: Look at each answer choice.
Both are only physical changes.
Water evaporating is a physical change. But baking cookies is not.
Both are chemical changes.
Baking cookies is a chemical change. But water evaporating from a puddle is not.
Both are caused by heating.
Both changes are caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question:
What do these two changes have in common?
erosion caused by wind
ice melting in a cup

Choices:
A. Both are caused by cooling.
B. Both are only physical changes.
C. Both are chemical changes.
D. Both are caused by heating.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Erosion caused by wind is a physical change. The wind carries away tiny pieces of rock. But the pieces of rock do not become a different type of matter.
Ice melting in a cup is a change of state. So, it is a physical change. The solid ice becomes liquid, but it is still made of water.
The links between atoms in the water molecules do not change. So, a different type of matter is not formed.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Ice melting is caused by heating. But erosion caused by wind is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: What is the expected ratio of offspring with a normal-sized body to offspring with a dwarf body? Choose the most likely ratio.

Choices:
A. 0:4
B. 3:1
C. 4:0
D. 1:3
E. 2:2

In a group of rats, some individuals have a normal-sized body and others have a dwarf body. In this group, the gene for the body size trait has two alleles. The allele for a dwarf body (b) is recessive to the allele for a normal-sized body (B).
This Punnett square shows a cross between two rats.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

To determine how many boxes in the Punnett square represent offspring with a normal-sized body or a dwarf body, consider whether each phenotype is the dominant or recessive allele's version of the body size trait. The question tells you that the b allele, which is for a dwarf body, is recessive to the B allele, which is for a normal-sized body.
A normal-sized body is the dominant allele's version of the body size trait. A rat with the dominant version of the body size trait must have at least one dominant allele for the body size gene. So, offspring with a normal-sized body must have the genotype BB or Bb.
All 4 boxes in the Punnett square have the genotype BB or Bb.
A dwarf body is the recessive allele's version of the body size trait. A rat with the recessive version of the body size trait must have only recessive alleles for the body size gene. So, offspring with a dwarf body must have the genotype bb.
There are 0 boxes in the Punnett square with the genotype bb.
So, the expected ratio of offspring with a normal-sized body to offspring with a dwarf body is 4:0. This means that, based on the Punnett square, this cross will always produce offspring with a normal-sized body. This cross is expected to never produce offspring with a dwarf body.

natural science


Question: Select the fish below.

Choices:
A. poison dart frog
B. penguin
C. water buffalo
D. great white shark

Fish live underwater. They have fins, not limbs.
Fish are cold-blooded. The body temperature of cold-blooded animals depends on their environment.
A Banggai cardinalfish is an example of a fish.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

A penguin is a bird. It has feathers, two wings, and a beak.
Penguins live near water. Penguins cannot fly! They use their wings to swim.
A water buffalo is a mammal. It has hair and feeds its young milk.
Water buffaloes live in Asia. Some people raise water buffaloes for their milk.
A great white shark is a fish. It lives underwater. It has fins, not limbs.
Great white sharks can live for up to 70 years.
A poison dart frog is an amphibian. It has moist skin and begins its life in water.
Poison dart frogs come in many bright colors. Their bright color warns other animals that these frogs are poisonous.

natural science


Question:
What do these two changes have in common?
a piece of pear turning brown
acid rain weathering a marble statue

Choices:
A. Both are caused by cooling.
B. Both are only physical changes.
C. Both are chemical changes.
D. Both are caused by heating.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
A piece of a pear turning brown is a chemical change. The substances in the pear react with oxygen in the air and turn into a different type of matter.
If you scrape off the brown part of the pear, the inside will still be white. The inside hasn't touched the air. So the chemical change hasn't happened to that part of the pear.
Acid rain weathering a marble statue is a chemical change. The acid rain reacts with the outside of the statue and breaks it down into a different type of matter. This new matter is then washed away by the rain. Acid rain is a type of pollution. It forms when smoke from automobiles and factories mixes with water in clouds.
Acid rain is a type of pollution. It forms when automobiles and factories release smoke containing sulfur or nitrogen. Some of these chemicals react with water in the atmosphere. The reaction forms droplets of water that can fall back to the ground as acid rain.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Which of the following organisms is the omnivore in this food web?

Choices:
A. black racer
B. gray fox
C. black bear
D. silver maple

Below is a food web from Shenandoah National Park, a forest ecosystem in Virginia.
A food web models how the matter eaten by organisms moves through an ecosystem. The arrows in a food web represent how matter moves between organisms in an ecosystem.

A food web is a model.
A food web shows where organisms in an ecosystem get their food. Models can make things in nature easier to understand because models can represent complex things in a simpler way. If a food web showed every organism in an ecosystem, the food web would be hard to understand. So, each food web shows how some organisms in an ecosystem can get their food.
Arrows show how matter moves.
A food web has arrows that point from one organism to another. Each arrow shows the direction that matter moves when one organism eats another organism. An arrow starts from the organism that is eaten. The arrow points to the organism that is doing the eating.
An organism in a food web can have more than one arrow pointing from it. This shows that the organism is eaten by more than one other organism in the food web.
An organism in a food web can also have more than one arrow pointing to it. This shows that the organism eats more than one other organism in the food web.

Omnivores are consumers that eat both producers and other consumers. So, an omnivore has arrows pointing to it from at least one producer and at least one consumer.
The black bear has an arrow pointing to it from the persimmon tree, which is a producer. The black bear also has arrows pointing to it from the swallowtail caterpillar and the beaver, which are consumers. The black bear eats a producer and consumers, so it is an omnivore.
The gray fox has two arrows pointing to it. These arrows start from the swallowtail caterpillar and the pine vole, which are both consumers.  So, the gray fox is a consumer but not an omnivore.
The pine vole has an arrow pointing to it from the persimmon tree, which is a producer. The pine vole also has an arrow pointing to it from the swallowtail caterpillar, which is a consumer. The pine vole eats a producer and a consumer, so it is an omnivore.
The silver maple does not have any arrows pointing to it. So, the silver maple is not an omnivore.
The black racer has only one arrow pointing to it. This arrow starts from the pine vole, which is a consumer. So, the black racer is a consumer but not an omnivore.

natural science


Question:
What do these two changes have in common?
plants making food from sunlight, air, and water
a penny tarnishing

Choices:
A. Both are chemical changes.
B. Both are caused by heating.
C. Both are only physical changes.
D. Both are caused by cooling.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Plants making food is a chemical change. Plants use energy from sunlight to change air and water into food. The food is sugar. Sugar is a different type of matter than air or water.
Metal turning less shiny over time is called tarnishing. A penny tarnishing is a chemical change. When air touches the penny, the surface of the penny changes into a different type of matter. This matter makes the penny dull.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: How long is a human front tooth?

Choices:
A. 14 kilometers
B. 14 meters
C. 14 millimeters
D. 14 centimeters

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using metric units, length can be written with units of millimeters, centimeters, meters, or kilometers. One meter contains 100 centimeters or 1,000 millimeters. So, 1 meter is larger than 1 centimeter, and 1 centimeter is larger than 1 millimeter.
The tip of the pencil shown here is only 1 millimeter wide, but the pencil is about 16 centimeters long.
A red fox is about 1 meter long. The Sydney Harbour Bridge in Australia is about 1,000 meters, or 1 kilometer, in length.

The best estimate for the length of a human front tooth is 14 millimeters.
14 centimeters, 14 meters, and 14 kilometers are all too long.

natural science


Question: How long is a sofa?

Choices:
A. 3 centimeters
B. 3 meters
C. 3 millimeters
D. 3 kilometers

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using metric units, length can be written with units of millimeters, centimeters, meters, or kilometers. One meter contains 100 centimeters or 1,000 millimeters. So, 1 meter is larger than 1 centimeter, and 1 centimeter is larger than 1 millimeter.
The tip of the pencil shown here is only 1 millimeter wide, but the pencil is about 16 centimeters long.
A red fox is about 1 meter long. The Sydney Harbour Bridge in Australia is about 1,000 meters, or 1 kilometer, in length.

The best estimate for the length of a sofa is 3 meters.
3 millimeters and 3 centimeters are too short. 3 kilometers is too long.

natural science


Question: How long is a drinking straw?

Choices:
A. 10 feet
B. 10 inches
C. 10 miles
D. 10 yards

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a drinking straw is 10 inches.
10 feet, 10 yards, and 10 miles are all too long.

natural science

Choose customary units of distance, mass, and volume


Question: What is the probability that a Syrian hamster produced by this cross will have long fur?

Choices:
A. 0/4
B. 3/4
C. 2/4
D. 1/4
E. 4/4

In a group of Syrian hamsters, some individuals have short fur and others have long fur. In this group, the gene for the fur length trait has two alleles. The allele for short fur (F) is dominant over the allele for long fur (f).
This Punnett square shows a cross between two Syrian hamsters.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science


Question: How long is a rowboat?

Choices:
A. 4 miles
B. 4 feet
C. 4 yards
D. 4 inches

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a rowboat is 4 yards.
4 inches and 4 feet are too short. 4 miles is too long.

natural science


Question:
What do these two changes have in common?
rust forming on a bike frame
a penny tarnishing

Choices:
A. Both are only physical changes.
B. Both are chemical changes.
C. Both are caused by heating.
D. Both are caused by cooling.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Rust forming on a bike frame is a chemical change. The metal on the bike changes into rust. Metal and rust are different types of matter.
Metal turning less shiny over time is called tarnishing. A penny tarnishing is a chemical change. When air touches the penny, the surface of the penny changes into a different type of matter. This matter makes the penny dull.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: How long is a long-distance running race?

Choices:
A. 42 kilometers
B. 42 meters
C. 42 centimeters
D. 42 millimeters

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using metric units, length can be written with units of millimeters, centimeters, meters, or kilometers. One meter contains 100 centimeters or 1,000 millimeters. So, 1 meter is larger than 1 centimeter, and 1 centimeter is larger than 1 millimeter.
The tip of the pencil shown here is only 1 millimeter wide, but the pencil is about 16 centimeters long.
A red fox is about 1 meter long. The Sydney Harbour Bridge in Australia is about 1,000 meters, or 1 kilometer, in length.

The best estimate for the length of a long-distance running race is 42 kilometers.
42 millimeters, 42 centimeters, and 42 meters are all too short.

natural science


Question:
What do these two changes have in common?
making paper from wood
roasting a marshmallow over a campfire

Choices:
A. Both are caused by heating.
B. Both are caused by cooling.
C. Both are only physical changes.
D. Both are chemical changes.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Making paper from wood is a chemical change. Paper is made by mixing tiny pieces of wood with special chemicals. The wood reacts with the chemicals to form pulp. Wood and pulp are different types of matter.
Roasting a marshmallow is a chemical change. The type of matter on the outside of the marshmallow changes. As a marshmallow is roasted, it turns brown and crispy.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Roasting is caused by heating. But making paper from wood is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question:
What do these two changes have in common?
milk going sour
baking a loaf of bread

Choices:
A. Both are caused by heating.
B. Both are only physical changes.
C. Both are caused by cooling.
D. Both are chemical changes.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Milk going sour is a chemical change. The type of matter in the milk slowly changes. The new matter that is formed gives the milk its sour taste.
Baking a loaf of bread is a chemical change. Bread is made from dough. Baking turns the dough into bread. The bread is a different type of matter than the dough.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Baking is caused by heating. But milk going sour is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question:
What do these two changes have in common?
ice melting in a cup
dew appearing on grass in the morning

Choices:
A. Both are caused by heating.
B. Both are caused by cooling.
C. Both are only physical changes.
D. Both are chemical changes.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Ice melting in a cup is a change of state. So, it is a physical change. The solid ice becomes liquid, but it is still made of water.
The links between atoms in the water molecules do not change. So, a different type of matter is not formed.
Dew appearing on grass in the morning is a change of state. So, it is a physical change. Water vapor in the air touches the cool grass and becomes liquid.
The water vapor changes state to become dew, but it is still made of water. A different type of matter is not formed.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Ice melting is caused by heating. But dew appearing on grass is not.
Both are caused by cooling.
Dew appears when water vapor in the air condenses into a liquid on the grass. This is caused by cooling. But ice melting is not.

natural science