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Which of these states is farthest north?

closed choice

grade2

social science

geography

Geography

Read a map: cardinal directions

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west. A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction. The north arrow points to the North Pole. On most maps, north is at the top of the map.

To find the answer, look at the compass rose. Look at which way the north arrow is pointing. West Virginia is farthest north.

Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

closed choice

grade8

natural science

physics

Particle motion and energy

Identify how particle motion affects temperature and pressure

The temperature of a substance depends on the average kinetic energy of the particles in the substance. The higher the average kinetic energy of the particles, the higher the temperature of the substance. The kinetic energy of a particle is determined by its mass and speed. For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.

The particles in both samples have the same average speed, but each particle in sample B has more mass than each particle in sample A. So, the particles in sample B have a higher average kinetic energy than the particles in sample A. Because the particles in sample B have the higher average kinetic energy, sample B must have the higher temperature.

Which of these organisms contains matter that was once part of the phytoplankton?

Below is a food web from an ocean ecosystem in Monterey Bay, off the coast of California. 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.

closed choice

grade6

natural science

biology

Ecological interactions

Interpret food webs II

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 phytoplankton. The only arrow pointing to the sea otter starts from the sea urchin. The only arrow pointing to the sea urchin starts from the kelp. No arrow points to the kelp. So, in this food web, matter does not move from the phytoplankton to the sea otter.There are two paths matter can take from the phytoplankton to the plainfin midshipman: phytoplankton->plainfin midshipman. phytoplankton->zooplankton->plainfin midshipman. There is one path matter can take from the phytoplankton to the black rockfish: phytoplankton->zooplankton->black rockfish. There is one path matter can take from the phytoplankton to the zooplankton: phytoplankton->zooplankton.

Which solution has a higher concentration of blue particles?

The diagram below is a model of two solutions. Each blue ball represents one particle of solute.

closed choice

grade8

natural science

chemistry

Solutions

Compare concentrations of solutions

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent. The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent. concentration = particles of solute / volume of solvent

In Solution A and Solution B, the blue particles represent the solute. To figure out which solution has a higher concentration of blue particles, look at both the number of blue particles and the volume of the solvent in each container. Use the concentration formula to find the number of blue particles per milliliter. Solution A and Solution B have the same number of blue particles per milliliter. So, their concentrations are the same.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

closed choice

grade3

natural science

physics

Magnets

Compare strengths of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the strength of a magnetic force between two magnets by changing the distance between them. The magnetic force is stronger when the magnets are closer together.

Distance affects the strength of the magnetic force. When magnets are closer together, the magnetic force between them is stronger. The magnets in Pair 1 are closer together than the magnets in Pair 2. So, the magnetic force is stronger in Pair 1 than in Pair 2.

What does pollen help a plant do?

The male part of a flower makes pollen.

closed choice

grade4

natural science

biology

Plants

Describe and construct flowering plant life cycles

Many plants have flowers. These plants can use their flowers to reproduce, or make new plants like themselves. How do plants use their flowers to reproduce? First, the male part of the flower makes pollen, and the female part makes eggs. Animals, wind, or water can move pollen. Pollination is what happens when pollen is moved to the female part of the flower. After pollination, sperm from the pollen can combine with the eggs. This is called fertilization. The fertilized eggs grow into seeds. The fruit grows around the seeds. Later, a seed can fall out of the fruit. It can germinate, or start to grow into a new plant.

Pollen helps the flower make seeds. After pollination, sperm cells from the pollen can combine with the eggs. These fertilized eggs can grow into seeds. Pollen does not help a plant grow bigger or grow leaves.

Which property matches this object?

Select the better answer.

closed choice

grade3

natural science

physics

Materials

Identify properties of an object

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.

Look at the object. Think about each property. A flexible object can be folded or bent without breaking easily. The helium balloons are flexible. A sticky object can attach or stick to other things. The helium balloons are not sticky.

Which property do these three objects have in common?

Select the best answer.

closed choice

grade4

natural science

physics

Materials

Compare properties of objects

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it. Different objects can have properties in common. You can use these properties to put objects into groups. Grouping objects by their properties is called classification.

Look at each object. For each object, decide if it has that property. A hard object does not change shape when pressed or squeezed. None of the objects are hard. Yellow is a color. This color is yellow. None of the objects are yellow. A soft object changes shape when pressed or squeezed. All three objects are soft. The property that all three objects have in common is soft.

Select the fish below.

Fish live underwater. They have fins, not limbs. A tiger shark is an example of a fish.

closed choice

grade3

natural science

biology

Classification

Identify mammals, birds, fish, reptiles, and amphibians

Birds, mammals, fish, reptiles, and amphibians are groups of animals. The animals in each group have traits in common. Scientists sort animals into groups based on traits they have in common. This process is called classification.

A cardinalfish is a fish. It lives underwater. It has fins, not limbs. Cardinalfish often live near coral reefs. They are nocturnal, which means that they are active mostly at night. A black howler is a mammal. It has hair and feeds its young milk. Howler monkeys have loud calls, or howls. Their calls can be heard over three miles away!

Complete the statement. Tungsten carbide is ().

The model below represents tungsten carbide. Tungsten carbide can be used to make the tips of ballpoint pens.

closed choice

grade7

natural science

chemistry

Atoms and molecules

Classify elementary substances and compounds using models

There are more than 100 different chemical elements, or types of atoms. Chemical elements make up all of the substances around you. A substance may be composed of one chemical element or multiple chemical elements. Substances that are composed of only one chemical element are elementary substances. Substances that are composed of multiple chemical elements bonded together are compounds. Every chemical element is represented by its own atomic symbol. An atomic symbol may consist of one capital letter, or it may consist of a capital letter followed by a lowercase letter. For example, the atomic symbol for the chemical element fluorine is F, and the atomic symbol for the chemical element beryllium is Be. Scientists use different types of models to represent substances whose atoms are bonded in different ways. One type of model is a ball-and-stick model. The ball-and-stick model below represents the compound pyrite. In a ball-and-stick model, the balls represent atoms, and the sticks represent bonds. Notice that the balls in the model above are not all the same color. Each color represents a different chemical element. The legend shows the color and the atomic symbol for each chemical element in the substance.

Use the model to determine whether tungsten carbide is an elementary substance or a compound. Step 1: Interpret the model. . Use the legend to determine the chemical element represented by each color. The colors and atomic symbols from the legend are shown in the table below. The table also includes the names of the chemical elements represented in the model. You can see from the model that tungsten carbide is composed of carbon atoms and tungsten atoms bonded together. Step 2: Determine whether the substance is an elementary substance or a compound. You know from Step 1 that tungsten carbide is composed of two chemical elements: carbon and tungsten. Since tungsten carbide is composed of multiple chemical elements bonded together, tungsten carbide is a compound.

What is the expected ratio of offspring with a hairy body to offspring with a hairless body? Choose the most likely ratio.

In a group of deer mice, some individuals have a hairy body and others have a hairless body. In this group, the gene for the body hair trait has two alleles. The allele for a hairy body (B) is dominant over the allele for a hairless body (b). This Punnett square shows a cross between two deer mice.

closed choice

grade8

natural science

biology

Genes to traits

Use Punnett squares to calculate ratios of offspring types

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 hairy body or a hairless body, consider whether each phenotype is the dominant or recessive allele's version of the body hair trait. The question tells you that the B allele, which is for a hairy body, is dominant over the b allele, which is for a hairless body. A hairy body is the dominant allele's version of the body hair trait. A deer mouse with the dominant version of the body hair trait must have at least one dominant allele for the body hair gene. So, offspring with a hairy body must have the genotype BB or Bb. All 4 boxes in the Punnett square have the genotype BB or Bb. A hairless body is the recessive allele's version of the body hair trait. A deer mouse with the recessive version of the body hair trait must have only recessive alleles for the body hair gene. So, offspring with a hairless 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 hairy body to offspring with a hairless body is 4:0. This means that, based on the Punnett square, this cross will always produce offspring with a hairy body. This cross is expected to never produce offspring with a hairless body.

Is a scarf a solid or a liquid?

closed choice

grade2

natural science

physics

States of matter

Classify matter as solid or liquid

Solid and liquid are states of matter. Matter is anything that takes up space. Matter can come in different states, or forms. When matter is a solid, it has a shape of its own. Some solids can be bent or broken easily. Others are hard to bend or break. A glass cup is a solid. A sock is also a solid. When matter is a liquid, it takes the shape of its container. Think about pouring a liquid from a cup into a bottle. The shape of the liquid is different in the cup than in the bottle. But the liquid still takes up the same amount of space. Juice is a liquid. Honey is also a liquid.

A scarf is a solid. You can fold a scarf. But it will still have a size and shape of its own.

Which animal is also adapted for climbing trees?

s live in rain forests on the island of Sumatra in Asia. They climb trees to find food and shelter. The orangutan's hands and feet are adapted for climbing trees. Figure: Sumatran orangutan.

closed choice

grade4

natural science

biology

Adaptations

Animal adaptations: feet and limbs

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors. The shape of an animal's feet is one example of an adaptation. Animals' feet can be adapted in different ways. For example, webbed feet might help an animal swim. Feet with thick fur might help an animal walk on cold, snowy ground.

Look at the picture of the Sumatran orangutan. The Sumatran orangutan has long fingers and toes. It is adapted for climbing trees. The Sumatran orangutan uses its long fingers and toes to hold on to branches while climbing. Now look at each animal. Figure out which animal has a similar adaptation. The red-handed tamarin has long fingers and toes. It is adapted for climbing trees. The takin has four hoofed feet. It is not adapted for climbing trees. The takin uses its feet to walk and run.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different shapes.

closed choice

grade5

natural science

physics

Magnets

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by changing the distance between them. The magnitude of the magnetic force is smaller when there is a greater distance between the magnets.

The magnets in Pair 2 attract. The magnets in Pair 1 repel. But whether the magnets attract or repel affects only the direction of the magnetic force. It does not affect the magnitude of the magnetic force. Distance affects the magnitude of the magnetic force. When there is a greater distance between magnets, the magnitude of the magnetic force between them is smaller. There is a greater distance between the magnets in Pair 2 than in Pair 1. So, the magnitude of the magnetic force is smaller in Pair 2 than in Pair 1.

Is chalk a solid, a liquid, or a gas?

closed choice

grade3

natural science

physics

States of matter

Classify matter as solid, liquid, or gas

Solid, liquid, and gas are states of matter. Matter is anything that takes up space. Matter can come in different states, or forms. When matter is a solid, it has a definite volume and a definite shape. So, a solid has a size and shape of its own. Some solids can be easily folded, bent, or broken. A piece of paper is a solid. Also, some solids are very small. A grain of sand is a solid. When matter is a liquid, it has a definite volume but not a definite shape. So, a liquid has a size of its own, but it does not have a shape of its own. Think about pouring juice from a bottle into a cup. The juice still takes up the same amount of space, but it takes the shape of the bottle. Some liquids do not pour as easily as others. Honey and milk are both liquids. But pouring honey takes more time than pouring milk. When matter is a gas, it does not have a definite volume or a definite shape. A gas expands, or gets bigger, until it completely fills a space. A gas can also get smaller if it is squeezed into a smaller space. Many gases are invisible. Air is a gas.

Chalk is a solid. You can easily break chalk into pieces. But each piece will still have a size and shape of its own.

Which solution has a higher concentration of yellow particles?

The diagram below is a model of two solutions. Each yellow ball represents one particle of solute.

closed choice

grade7

natural science

chemistry

Solutions

Compare concentrations of solutions

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent. The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent. concentration = particles of solute / volume of solvent

In Solution A and Solution B, the yellow particles represent the solute. To figure out which solution has a higher concentration of yellow particles, look at both the number of yellow particles and the volume of the solvent in each container. Use the concentration formula to find the number of yellow particles per milliliter. Solution B has more yellow particles per milliliter. So, Solution B has a higher concentration of yellow particles.

Which animal's feet are also adapted for swimming?

s spend much of their lives at sea. They eat mostly fish, which they catch while swimming and diving. The feet of the are adapted for swimming. Figure: Atlantic puffin.

closed choice

grade3

natural science

biology

Adaptations

Animal adaptations: feet and limbs

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors. The shape of an animal's feet is one example of an adaptation. Animals' feet can be adapted in different ways. For example, webbed feet might help an animal swim. Feet with thick fur might help an animal walk on cold, snowy ground.

Look at the picture of the Atlantic puffin. The Atlantic puffin has webbed feet. Its feet are adapted for swimming. As it swims, the Atlantic puffin uses its webbed feet to push itself through water. Now look at each animal. Figure out which animal has a similar adaptation. The blue-footed booby has webbed feet. Its feet are adapted for swimming. The tokay gecko has wide, sticky toes. Its feet are not adapted for swimming. The tokay gecko uses its feet to climb trees and walk on leaves.

Which solution has a higher concentration of green particles?

The diagram below is a model of two solutions. Each green ball represents one particle of solute.

closed choice

grade6

natural science

chemistry

Solutions

Compare concentrations of solutions

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent. The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent. concentration = particles of solute / volume of solvent

In Solution A and Solution B, the green particles represent the solute. To figure out which solution has a higher concentration of green particles, look at both the number of green particles and the volume of the solvent in each container. Use the concentration formula to find the number of green particles per milliliter. Solution A has more green particles per milliliter. So, Solution A has a higher concentration of green particles.

Which cones make pollen?

This diagram shows the life cycle of a pine tree.

closed choice

grade8

natural science

biology

Plant reproduction

Angiosperm and conifer life cycles

Gymnosperms are plants that have seeds but not flowers. Conifers are a type of a gymnosperm. Instead of flowers, conifers have cones. Conifers use their cones for sexual reproduction. Most conifer trees have both male and female cones. The male cones produce pollen. The female cones produce eggs and a sticky substance on the edge of the cone. Male cones release pollen into the wind. Pollination happens when pollen lands on and sticks to the female cones. Self-pollination happens when pollen sticks to a female cone on the same tree. Cross-pollination happens when pollen sticks to a female cone on a different tree. After pollination, sperm from the pollen fuse with eggs at the base of the female cone's scales. This is called fertilization. The fertilized eggs grow into seeds inside the female cone. Conifer seeds are released from the fertilized cones. Many conifer seeds have wing-like structures. They can be carried long distances by the wind. When a seed lands on the ground, it can germinate and grow into a new plant. The new plant can grow cones and begin the conifer life cycle again.

Male cones make pollen. When pollen sticks to a female cone, the female cone becomes pollinated. Pollinated cones do not produce pollen.

Complete the statement. Palladium is ().

The model below represents palladium. Palladium is a metal that reacts with the gases produced by car engines to make the gases less harmful.

closed choice

grade7

natural science

chemistry

Atoms and molecules

Classify elementary substances and compounds using models

There are more than 100 different chemical elements, or types of atoms. Chemical elements make up all of the substances around you. A substance may be composed of one chemical element or multiple chemical elements. Substances that are composed of only one chemical element are elementary substances. Substances that are composed of multiple chemical elements bonded together are compounds. Every chemical element is represented by its own atomic symbol. An atomic symbol may consist of one capital letter, or it may consist of a capital letter followed by a lowercase letter. For example, the atomic symbol for the chemical element fluorine is F, and the atomic symbol for the chemical element beryllium is Be. Scientists use different types of models to represent substances whose atoms are bonded in different ways. One type of model is a space-filling model. The space-filling model below represents the elementary substance copper. In a space-filling model, the balls represent atoms that are bonded together. The color of a ball represents a specific chemical element. The atomic symbol for that chemical element is shown in the legend.

Use the model to determine whether palladium is an elementary substance or a compound. Step 1: Interpret the model. In the space-filling model shown above, all of the balls are the same color: . The legend shows that dark blue represents the chemical element with the atomic symbol Pd. So, the model shows you that palladium is composed of one chemical element. Step 2: Determine whether the substance is an elementary substance or a compound. You know from Step 1 that palladium is composed of only one chemical element. So, palladium is an elementary substance.

In this food chain, the Mojave yucca is a producer. Why?

This diagram shows a food chain from a desert ecosystem in Southern California.

closed choice

grade3

natural science

biology

Ecosystems

Identify roles in food chains

Every living thing needs food to stay alive. Living things get their food in different ways. A food chain shows how living things in an ecosystem get their food. Producers make their own food. Many producers use carbon dioxide, water, and sunlight to make sugar. This sugar is food for the producer. Consumers eat other living things. Consumers cannot make their own food.

In this food chain, the Mojave yucca is a producer because it makes its own food. The Mojave yucca uses carbon dioxide, water, and sunlight to make its own food.

Which of these states is farthest east?

closed choice

grade2

social science

geography

Geography

Read a map: cardinal directions

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west. A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction. The north arrow points to the North Pole. On most maps, north is at the top of the map.

To find the answer, look at the compass rose. Look at which way the east arrow is pointing. Arkansas is farthest east.

Will these magnets attract or repel each other?

Two magnets are placed as shown. Hint: Magnets that attract pull together. Magnets that repel push apart.

closed choice

grade2

natural science

physics

Magnets

Identify magnets that attract or repel

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles, called north and south. Here are some examples of magnets. The north pole of each magnet is marked N, and the south pole is marked S. If different poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

Will these magnets attract or repel? To find out, look at which poles are closest to each other. The north pole of one magnet is closest to the south pole of the other magnet. Poles that are different attract. So, these magnets will attract each other.

Select the chemical formula for this molecule.

closed choice

grade7

natural science

chemistry

Atoms and molecules

Identify chemical formulas for ball-and-stick models

Every substance around you is made up of atoms. Atoms can link together to form molecules. The links between atoms in a molecule are called chemical bonds. Different molecules are made up of different chemical elements, or types of atoms, bonded together. Scientists use both ball-and-stick models and chemical formulas to represent molecules. A ball-and-stick model of a molecule is shown below. The balls represent atoms. The sticks represent the chemical bonds between the atoms. Balls that are different colors represent atoms of different elements. The element that each color represents is shown in the legend. Every element has its own abbreviation, called its atomic symbol. Every chemical element is represented by its own symbol. For some elements, that symbol is one capital letter. For other elements, it is one capital letter followed by one lowercase letter. For example, the symbol for the element boron is B and the symbol for the element chlorine is Cl. The molecule shown above has one boron atom and three chlorine atoms. A chemical bond links each chlorine atom to the boron atom. The chemical formula for a substance contains the atomic symbol for each element in the substance. Many chemical formulas also contain subscripts. A subscript is small text placed lower than the normal line of text. Each subscript in a chemical formula is placed after the symbol for an element and tells you how many atoms of that element that symbol represents. If there is no subscript after a symbol, that symbol represents one atom. So, the chemical formula for a substance tells you which elements make up that substance. It also tells you the ratio of the atoms of those elements in the substance. For example, the chemical formula below tells you that there are three chlorine atoms for every one boron atom in the substance. This chemical formula represents the same substance as the ball-and-stick model shown above.

H is the symbol for hydrogen. According to the legend, hydrogen atoms are shown in light gray. F is the symbol for fluorine. According to the legend, fluorine atoms are shown in light green. This ball-and-stick model shows a molecule with one hydrogen atom and one fluorine atom. The chemical formula will contain the symbols H and F. There is one hydrogen atom, so H will not have a subscript. There is one fluorine atom, so F will not have a subscript. The correct formula is HF. The diagram below shows how each part of the chemical formula matches with each part of the model above.

During this time, thermal energy was transferred from () to ().

Two identical aquariums were next to an open window. One aquarium had a plastic cover on it, and the other was uncovered. This table shows how the temperature of each aquarium changed over 1.5hours.

closed choice

grade7

natural science

physics

Thermal energy

Compare thermal energy transfers

A change in an object's temperature indicates a change in the object's thermal energy: An increase in temperature shows that the object's thermal energy increased. So, thermal energy was transferred into the object from its surroundings. A decrease in temperature shows that the object's thermal energy decreased. So, thermal energy was transferred out of the object to its surroundings.

The temperature of each aquarium decreased, which means that the thermal energy of each aquarium decreased. So, thermal energy was transferred from each aquarium to the surroundings.

Select the organism in the same genus as the crystal jellyfish.

This organism is a crystal jellyfish. Its scientific name is Aequorea victoria.

closed choice

grade7

natural science

biology

Classification and scientific names

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words. The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits. A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus. Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus. Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

A crystal jellyfish's scientific name is Aequorea victoria. The first word of its scientific name is Aequorea. This organism and the crystal jellyfish are in the same genus and the same species! Both organisms have the same scientific name, Aequorea victoria. Goura victoria and Aequorea victoria are not in the same genus. These organisms are not in the same genus, but part of their scientific names is the same. Goura victoria and Aequorea victoria have the same species name within their genus, victoria. But the first words of their scientific names are different. Goura victoria is in the genus Goura, and Aequorea victoria is in the genus Aequorea. Larus occidentalis is in the genus Larus. The first word of its scientific name is Larus. So, Larus occidentalis and Aequorea victoria are not in the same genus.

Which solution has a higher concentration of green particles?

The diagram below is a model of two solutions. Each green ball represents one particle of solute.

closed choice

grade7

natural science

chemistry

Solutions

Compare concentrations of solutions

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent. The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent. concentration = particles of solute / volume of solvent

In Solution A and Solution B, the green particles represent the solute. To figure out which solution has a higher concentration of green particles, look at both the number of green particles and the volume of the solvent in each container. Use the concentration formula to find the number of green particles per milliliter. Solution A has more green particles per milliliter. So, Solution A has a higher concentration of green particles.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

closed choice

grade3

natural science

physics

Magnets

Compare strengths of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the strength of a magnetic force between two magnets by changing the distance between them. The magnetic force is stronger when the magnets are closer together.

Distance affects the strength of the magnetic force. When magnets are closer together, the magnetic force between them is stronger. The magnets in Pair 1 are closer together than the magnets in Pair 2. So, the magnetic force is stronger in Pair 1 than in Pair 2.

Which property do these four objects have in common?

Select the best answer.

closed choice

grade5

natural science

physics

Materials

Compare properties of objects

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it. Different objects can have properties in common. You can use these properties to put objects into groups. Grouping objects by their properties is called classification.

Look at each object. For each object, decide if it has that property. Sugar has a sweet taste. All four objects are sweet. A translucent object lets light through. But you cannot see clearly through a translucent object. The apple juice is translucent, but the chocolate bar and the peach are not. A fuzzy object is covered in soft hair. The chocolate bar and the jam are not fuzzy. The property that all four objects have in common is sweet.

Which type of force from the girl opens the window?

A girl applies a force to a window. She uses the force to open the window.

closed choice

grade3

natural science

physics

Force and motion

Identify pushes and pulls

A force is a push or a pull that one object applies to a second object. The direction of a push is away from the object that is pushing. The direction of a pull is toward the object that is pulling.

The girl applies a force to the window panes. This force opens the window. The direction of this force is away from the girl. This force is a push.

Which statement describes the Tallgrass Prairie National Preserve ecosystem?

Figure: Tallgrass Prairie National Preserve. Tallgrass Prairie National Preserve is a prairie grassland ecosystem in eastern Kansas. The preserve is named for its grass, which can grow over five feet tall. This type of grass once covered large parts of North America, but it is now rare. Most of the tallgrass in North America was destroyed to create farmland.

closed choice

grade8

natural science

biology

Ecosystems

Describe ecosystems

An environment includes all of the biotic, or living, and abiotic, or nonliving, things in an area. An ecosystem is created by the relationships that form among the biotic and abiotic parts of an environment. There are many different types of terrestrial, or land-based, ecosystems. Here are some ways in which terrestrial ecosystems can differ from each other: the pattern of weather, or climate the type of soil the organisms that live there

A prairie grassland is a type of ecosystem. Prairie grasslands have the following features: hot summers and cool winters, a medium amount of rain, and soil that is rich in nutrients. So, the following statement describes the Tallgrass Prairie National Preserve ecosystem: hot summers and cool winters, a medium amount of rain, and soil that is rich in nutrients. It has a medium amount of rain. The following statements do not describe Tallgrass Prairie National Preserve: hot summers and cool winters, a medium amount of rain, and soil that is rich in nutrients. It has soil that is poor in nutrients. It has cold winters and cool summers.

What is this tarantula's scientific name?

This species of tarantula was discovered near Folsom Prison in California. It was named after the musician Johnny Cash, who sang about the prison and was often called "The Man in Black."

closed choice

grade4

natural science

biology

Scientific names

Origins of scientific names

When a scientist identifies a new organism, he or she chooses its scientific name. Sometimes, an organism is named after the place where it was first found. Other times, an organism is named after the scientist who first identified it. Or, the scientific name might describe the organism's physical traits. Many of the words that make up scientific names are based on words from old languages, like Latin and classical Greek. Sometimes, English words are changed to make them sound more like Latin or Greek. The new words are then used in an organism's scientific name.

This organism's scientific name refers to Johnny Cash. The word johnnycashi refers to Johnny Cash. So, this tarantula's scientific name is Aphonopelma johnnycashi.

Which bird's beak is also adapted to get nectar out of long flowers?

Green violetears live in the forests of Central and South America. The shape of the 's beak is adapted to get nectar out of long flowers. Figure: green violetear.

closed choice

grade5

natural science

biology

Adaptations

Animal adaptations: beaks, mouths, and necks

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors. The shape of a bird's beak is one example of an adaptation. Birds' beaks can be adapted in different ways. For example, a sharp hooked beak might help a bird tear through meat easily. A short, thick beak might help a bird break through a seed's hard shell. Birds that eat similar food often have similar beaks.

Look at the picture of the green violetear. The green violetear has a long, thin beak. Its beak is adapted to get nectar out of long flowers. The green violetear's long, thin beak can reach deep into the flowers. Now look at each bird. Figure out which bird has a similar adaptation. The violet sabrewing has a long, thin beak. Its beak is adapted to get nectar out of long flowers. The ground hornbill has a large, long beak. Its beak is not adapted to get nectar out of long flowers. The ground hornbill uses its beak to catch, frogs, insects, and small mammals.

Which of these states is farthest north?

closed choice

grade4

social science

geography

Maps

Read a map: cardinal directions

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west. A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction. The north arrow points to the North Pole. On most maps, north is at the top of the map.

To find the answer, look at the compass rose. Look at which way the north arrow is pointing. Nebraska is farthest north.

What is the expected ratio of offspring with brown eyes to offspring with red eyes? Choose the most likely ratio.

In a group of guinea pigs, some individuals have brown eyes and others have red eyes. In this group, the gene for the eye color trait has two alleles. The allele for brown eyes (E) is dominant over the allele for red eyes (e). This Punnett square shows a cross between two guinea pigs.

closed choice

grade8

natural science

biology

Genes to traits

Use Punnett squares to calculate ratios of offspring types

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 brown eyes or red eyes, consider whether each phenotype is the dominant or recessive allele's version of the eye color trait. The question tells you that the E allele, which is for brown eyes, is dominant over the e allele, which is for red eyes. Brown eyes is the dominant allele's version of the eye color trait. A guinea pig with the dominant version of the eye color trait must have at least one dominant allele for the eye color gene. So, offspring with brown eyes must have the genotype EE or Ee. All 4 boxes in the Punnett square have the genotype EE or Ee. Red eyes is the recessive allele's version of the eye color trait. A guinea pig with the recessive version of the eye color trait must have only recessive alleles for the eye color gene. So, offspring with red eyes must have the genotype ee. There are 0 boxes in the Punnett square with the genotype ee. So, the expected ratio of offspring with brown eyes to offspring with red eyes is 4:0. This means that, based on the Punnett square, this cross will always produce offspring with brown eyes. This cross is expected to never produce offspring with red eyes.

Which of these states is farthest east?

closed choice

grade2

social science

geography

Geography

Read a map: cardinal directions

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west. A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction. The north arrow points to the North Pole. On most maps, north is at the top of the map.

To find the answer, look at the compass rose. Look at which way the east arrow is pointing. New York is farthest east.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different sizes.

closed choice

grade8

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by using magnets of different sizes. The magnitude of the magnetic force is smaller when the magnets are smaller.

Magnet sizes affect the magnitude of the magnetic force. Imagine magnets that are the same shape and made of the same material. The smaller the magnets, the smaller the magnitude of the magnetic force between them. Magnet A is the same size in both pairs. But Magnet B is smaller in Pair 1 than in Pair 2. So, the magnitude of the magnetic force is smaller in Pair 1 than in Pair 2.

Which of the following fossils is older? Select the more likely answer.

This diagram shows fossils in an undisturbed sedimentary rock sequence.

closed choice

grade8

natural science

earth-science

Fossils

Compare ages of fossils in a rock sequence

A fossil is the preserved evidence of an ancient organism. Some fossils are formed from body parts such as bones or shells. Other fossils, such as footprints or burrows, are formed from traces of an organism's activities. Fossils are typically found in sedimentary rocks. Sedimentary rocks usually form in layers. Over time, new layers are added on top of old layers in a series called a rock sequence. The layers in an undisturbed rock sequence are in the same order as when they formed. So, the deeper layers are older than the shallower layers. The relative ages of fossils can be determined from their positions in an undisturbed rock sequence. Older fossils are usually in deeper layers, and younger fossils are usually in shallower layers.

Look again at the fossils in the rock sequence diagram. Compare the positions of these fossils to determine which one is older: The dinosaur footprint fossil is in a deeper layer in the rock sequence than the fern fossil. So, the dinosaur footprint fossil is most likely older than the fern fossil.

Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

closed choice

grade7

natural science

physics

Particle motion and energy

Identify how particle motion affects temperature and pressure

The temperature of a substance depends on the average kinetic energy of the particles in the substance. The higher the average kinetic energy of the particles, the higher the temperature of the substance. The kinetic energy of a particle is determined by its mass and speed. For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.

The particles in both samples have the same average speed, but each particle in sample A has more mass than each particle in sample B. So, the particles in sample A have a higher average kinetic energy than the particles in sample B. Because the particles in sample A have the higher average kinetic energy, sample A must have the higher temperature.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different sizes and shapes.

closed choice

grade7

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by using magnets of different sizes. The magnitude of the magnetic force is greater when the magnets are larger.

Magnet sizes affect the magnitude of the magnetic force. Imagine magnets that are the same shape and made of the same material. The larger the magnets, the greater the magnitude of the magnetic force between them. Magnet A is the same size in both pairs. But Magnet B is larger in Pair 2 than in Pair 1. So, the magnitude of the magnetic force is greater in Pair 2 than in Pair 1.

Which better describes the Shenandoah National Park ecosystem?

Figure: Shenandoah National Park. Shenandoah National Park is a temperate deciduous forest ecosystem in northern Virginia.

closed choice

grade3

natural science

biology

Ecosystems

Describe ecosystems

An ecosystem is formed when living and nonliving things interact in an environment. There are many types of ecosystems. Here are some ways in which ecosystems can differ from each other: the pattern of weather, or climate the type of soil or water the organisms that live there

A temperate deciduous forest is a type of ecosystem. Temperate deciduous forests have the following features: warm, wet summers and cold, wet winters, soil that is rich in nutrients, and only a few types of trees. So, Shenandoah National Park has warm, wet summers. It also has only a few types of trees.

Which continent is highlighted?

closed choice

grade5

social science

geography

Oceans and continents

Identify oceans and continents

A continent is one of the major land masses on the earth. Most people say there are seven continents.

This continent is North America.

Which ocean is highlighted?

closed choice

grade7

social science

geography

Physical Geography

Oceans and continents

Oceans are huge bodies of salt water. The world has five oceans. All of the oceans are connected, making one world ocean.

This is the Arctic Ocean.

Is a ring a solid or a liquid?

closed choice

grade2

natural science

physics

States of matter

Classify matter as solid or liquid

Solid and liquid are states of matter. Matter is anything that takes up space. Matter can come in different states, or forms. When matter is a solid, it has a shape of its own. Some solids can be bent or broken easily. Others are hard to bend or break. A glass cup is a solid. A sock is also a solid. When matter is a liquid, it takes the shape of its container. Think about pouring a liquid from a cup into a bottle. The shape of the liquid is different in the cup than in the bottle. But the liquid still takes up the same amount of space. Juice is a liquid. Honey is also a liquid.

A ring is a solid. A solid has a size and shape of its own. A ring keeps its shape, even when you take it off your finger.

Which material is this screw driver made of?

closed choice

grade2

natural science

physics

Materials

Identify multiple materials in objects

A material is a type of matter. Wood, glass, metal, and plastic are common materials. Some objects are made of just one material. Most nails are made of metal. Other objects are made of more than one material. This hammer is made of metal and wood.

Look at the picture of the screw driver. This screw driver is made of two different materials. The handle is made of plastic. The rest of the screw driver is made of metal. Metal is a good material for tools. Metal is hard and can be made into many shapes.

Which part of the collard plant do we usually eat?

People use collard plants for food. Photosynthesis makes food for the plant. We usually eat the part of the plant that does most of the photosynthesis.

closed choice

grade4

natural science

biology

Plants

Classify fruits and vegetables as plant parts

The fruits and vegetables we eat are parts of plants! Plants are made up of different structures. The different structures carry out important functions. The roots take in water and nutrients from the soil. They also hold the plant in place in the soil. The stem supports the plant. It carries food, water, and nutrients through the plant. The leaves are where most of the plant's photosynthesis happens. Photosynthesis is the process plants use to turn water, sunlight, and carbon dioxide into food. After they are pollinated, the flowers make seeds and fruit. The fruit contain the seeds. Each fruit grows from a pollinated flower. The seeds can grow into a new plant. Germination is when a seed begins to grow.

The part of the collard plant we usually eat is the leaves. They do most of the photosynthesis to make food for the plant.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different shapes.

closed choice

grade6

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by changing the distance between them. The magnitude of the magnetic force is greater when there is a smaller distance between the magnets.

The magnets in Pair 1 attract. The magnets in Pair 2 repel. But whether the magnets attract or repel affects only the direction of the magnetic force. It does not affect the magnitude of the magnetic force. Distance affects the magnitude of the magnetic force. When there is a smaller distance between magnets, the magnitude of the magnetic force between them is greater. There is a smaller distance between the magnets in Pair 2 than in Pair 1. So, the magnitude of the magnetic force is greater in Pair 2 than in Pair 1.

Which property matches this object?

Select the better answer.

closed choice

grade3

natural science

physics

Materials

Identify properties of an object

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.

Look at the object. Think about each property. A colorful object has one or more bright colors. The kite is colorful. A sticky object can attach or stick to other things. The kite is not sticky.

Which property matches this object?

Select the better answer.

closed choice

grade2

natural science

physics

Materials

Identify properties of an object

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells.

Look at the object. Think about each property. A shiny object reflects a lot of light. The silver ring is shiny. Yellow is a color. This color is yellow. The silver ring is not yellow.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different sizes.

closed choice

grade6

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by using magnets of different sizes. The magnitude of the magnetic force is smaller when the magnets are smaller.

Magnet sizes affect the magnitude of the magnetic force. Imagine magnets that are the same shape and made of the same material. The smaller the magnets, the smaller the magnitude of the magnetic force between them. Magnet A is the same size in both pairs. But Magnet B is smaller in Pair 1 than in Pair 2. So, the magnitude of the magnetic force is smaller in Pair 1 than in Pair 2.

Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

closed choice

grade8

natural science

physics

Particle motion and energy

Identify how particle motion affects temperature and pressure

The temperature of a substance depends on the average kinetic energy of the particles in the substance. The higher the average kinetic energy of the particles, the higher the temperature of the substance. The kinetic energy of a particle is determined by its mass and speed. For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.

The particles in both samples have the same average speed, but each particle in sample A has more mass than each particle in sample B. So, the particles in sample A have a higher average kinetic energy than the particles in sample B. Because the particles in sample A have the higher average kinetic energy, sample A must have the higher temperature.

In this food chain, the macroalgae is a producer. Why?

This diagram shows a food chain from the River Frome, a freshwater ecosystem in England.

closed choice

grade4

natural science

biology

Ecosystems

Identify roles in food chains

Every organism needs food to stay alive. Organisms get their food in different ways. A food chain shows how organisms in an ecosystem get their food. Producers make their own food. Many producers use carbon dioxide, water, and sunlight to make sugar. This sugar is food for the producer. Consumers eat other organisms. Consumers cannot make their own food.

In this food chain, the macroalgae is a producer because it makes its own food. The macroalgae uses carbon dioxide, water, and sunlight to make its own food.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

closed choice

grade7

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by changing the distance between them. The magnitude of the magnetic force is smaller when there is a greater distance between the magnets.

Distance affects the magnitude of the magnetic force. When there is a greater distance between magnets, the magnitude of the magnetic force between them is smaller. There is a greater distance between the magnets in Pair 1 than in Pair 2. So, the magnitude of the magnetic force is smaller in Pair 1 than in Pair 2.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

closed choice

grade6

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other.

The magnets in Pair 2 attract. The magnets in Pair 1 repel. But whether the magnets attract or repel affects only the direction of the magnetic force. It does not affect the magnitude of the magnetic force. Both magnet sizes and distance affect the magnitude of the magnetic force. The sizes of the magnets in Pair 1 are the same as in Pair 2. The distance between the magnets is also the same. So, the magnitude of the magnetic force is the same in both pairs.

Select the organism in the same genus as the Victoria crowned pigeon.

This organism is a Victoria crowned pigeon. Its scientific name is Goura victoria.

closed choice

grade5

natural science

biology

Scientific names

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words. The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits. A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus. Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus. Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

A Victoria crowned pigeon's scientific name is Goura victoria. The first word of its scientific name is Goura. Goura scheepmakeri is in the genus Goura. The first word of its scientific name is Goura. So, Goura scheepmakeri and Goura victoria are in the same genus. Aequorea victoria and Goura victoria are not in the same genus. These organisms are not in the same genus, but part of their scientific names is the same. Aequorea victoria and Goura victoria have the same species name within their genus, victoria. But the first words of their scientific names are different. Aequorea victoria is in the genus Aequorea, and Goura victoria is in the genus Goura. Falco sparverius is in the genus Falco. The first word of its scientific name is Falco. So, Falco sparverius and Goura victoria are not in the same genus.

Which material is this belt made of?

closed choice

grade2

natural science

physics

Materials

Identify multiple materials in objects

A material is a type of matter. Wood, glass, metal, and plastic are common materials. Some objects are made of just one material. Most nails are made of metal. Other objects are made of more than one material. This hammer is made of metal and wood.

Look at the picture of the belt. The belt is made of two materials. The buckle is made of metal. The rest of the belt is made of leather.

Select the organism in the same species as the North American beaver.

This organism is a North American beaver. Its scientific name is Castor canadensis.

closed choice

grade4

natural science

biology

Scientific names

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words. The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits. A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus. Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus. Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

A North American beaver's scientific name is Castor canadensis. Ovis orientalis does not have the same scientific name as a North American beaver. So, Castor canadensis and Ovis orientalis are not in the same species. Alouatta caraya does not have the same scientific name as a North American beaver. So, Castor canadensis and Alouatta caraya are not in the same species. Castor canadensis has the same scientific name as a North American beaver. So, these organisms are in the same species.

Is corundum a mineral or a rock?

Corundum has the following properties: fixed crystal structure solid pure substance found in nature very hard not made by organisms

closed choice

grade8

natural science

earth-science

Rocks and minerals

Identify rocks and minerals

Minerals are the building blocks of rocks. A rock can be made of one or more minerals. Minerals and rocks have the following properties: Property | Mineral | Rock It is a solid. | Yes | Yes It is formed in nature. | Yes | Yes It is not made by organisms. | Yes | Yes It is a pure substance. | Yes | No It has a fixed crystal structure. | Yes | No You can use these properties to tell whether a substance is a mineral, a rock, or neither. Look closely at the last three properties: Minerals and rocks are not made by organisms. Organisms make their own body parts. For example, snails and clams make their shells. Because they are made by organisms, body parts cannot be minerals or rocks. Humans are organisms too. So, substances that humans make by hand or in factories are not minerals or rocks. A mineral is a pure substance, but a rock is not. A pure substance is made of only one type of matter. Minerals are pure substances, but rocks are not. Instead, all rocks are mixtures. A mineral has a fixed crystal structure, but a rock does not. The crystal structure of a substance tells you how the atoms or molecules in the substance are arranged. Different types of minerals have different crystal structures, but all minerals have a fixed crystal structure. This means that the atoms and molecules in different pieces of the same type of mineral are always arranged the same way. However, rocks do not have a fixed crystal structure. So, the arrangement of atoms or molecules in different pieces of the same type of rock may be different!

Corundum has all the properties of a mineral. So, corundum is a mineral.

Does this passage describe the weather or the climate?

Figure: Marseille. Marseille is a town on the southern coast of France. Cold winds from the north, called mistral winds, are common in Marseille each year during late winter and early spring. Hint: Weather is what the atmosphere is like at a certain place and time. Climate is the pattern of weather in a certain place.

closed choice

grade5

natural science

earth-science

Weather and climate

Weather and climate around the world

The atmosphere is the layer of air that surrounds Earth. Both weather and climate tell you about the atmosphere. Weather is what the atmosphere is like at a certain place and time. Weather can change quickly. For example, the temperature outside your house might get higher throughout the day. Climate is the pattern of weather in a certain place. For example, summer temperatures in New York are usually higher than winter temperatures.

Read the passage carefully. Marseille is a town on the southern coast of France. Cold winds from the north, called mistral winds, are common in Marseille each year during late winter and early spring. The underlined part of the passage tells you about the usual wind patterns in Marseille. This passage does not describe what the weather is like on a particular day. So, this passage describes the climate.

Which property do these two objects have in common?

Select the better answer.

closed choice

grade2

natural science

physics

Materials

Compare properties of objects

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Different objects can have the same properties. You can use these properties to put objects into groups.

Look at each object. For each object, decide if it has that property. A sticky object can stick to other things. Neither of the objects are sticky. Yellow is a color. This color is yellow. Both objects are yellow. The property that both objects have in common is yellow.

Which property do these two objects have in common?

Select the better answer.

closed choice

grade2

natural science

physics

Materials

Compare properties of objects

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Different objects can have the same properties. You can use these properties to put objects into groups.

Look at each object. For each object, decide if it has that property. A breakable object will break into pieces if you drop it. Neither of the objects are breakable. A hard object keeps its shape when you squeeze it. Both objects are hard. The property that both objects have in common is hard.

Which ocean is highlighted?

closed choice

grade6

social science

geography

Physical Geography

Oceans and continents

Oceans are huge bodies of salt water. The world has five oceans. All of the oceans are connected, making one world ocean.

This is the Pacific Ocean.

Which property matches this object?

Select the better answer.

closed choice

grade3

natural science

physics

Materials

Identify properties of an object

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.

Look at the object. Think about each property. A rough object feels scratchy when you touch it. The water slide is not rough. Blue is a color. This color is blue. The water slide is blue.

Select the bird below.

Birds have feathers, two wings, and a beak. A woodpecker is an example of a bird.

closed choice

grade2

natural science

biology

Classification

Identify mammals, birds, fish, reptiles, and amphibians

Birds, mammals, fish, reptiles, and amphibians are groups of animals. The animals in each group have traits in common. Scientists sort animals into groups based on traits they have in common. This process is called classification.

An ostrich is a bird. It has feathers, two wings, and a beak. A Japanese tree frog is an amphibian. It has moist skin and begins its life in water.

Will these magnets attract or repel each other?

Two magnets are placed as shown. Hint: Magnets that attract pull together. Magnets that repel push apart.

closed choice

grade2

natural science

physics

Magnets

Identify magnets that attract or repel

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles, called north and south. Here are some examples of magnets. The north pole of each magnet is marked N, and the south pole is marked S. If different poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

Will these magnets attract or repel? To find out, look at which poles are closest to each other. The north pole of one magnet is closest to the south pole of the other magnet. Poles that are different attract. So, these magnets will attract each other.

Which better describes the Tibetan Plateau ecosystem?

Figure: Tibetan Plateau. The Tibetan Plateau is a tundra ecosystem located in Tibet, western China, and northern India.

closed choice

grade4

natural science

biology

Ecosystems

Describe ecosystems

An environment includes all of the biotic, or living, and abiotic, or nonliving, things in an area. An ecosystem is created by the relationships that form among the biotic and abiotic parts of an environment. There are many different types of terrestrial, or land-based, ecosystems. Here are some ways in which terrestrial ecosystems can differ from each other: the pattern of weather, or climate the type of soil the organisms that live there

A tundra is a type of ecosystem. Tundras have the following features: long, cold winters and short, cold summers, soil that is frozen year-round, and mostly small plants. So, the Tibetan Plateau has long, cold winters. It also has mostly small plants.

Will these magnets attract or repel each other?

Two magnets are placed as shown.

closed choice

grade5

natural science

physics

Magnets

Identify magnets that attract or repel

Magnets can pull or push on other magnets without touching them. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes are called magnetic forces. Magnetic forces are strongest at the magnets' poles, or ends. Every magnet has two poles: a north pole (N) and a south pole (S). Here are some examples of magnets. Their poles are shown in different colors and labeled. Whether a magnet attracts or repels other magnets depends on the positions of its poles. If opposite poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same, or like, poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

To predict if these magnets will attract or repel, look at which poles are closest to each other. The north pole of one magnet is closest to the south pole of the other magnet. Opposite poles attract. So, these magnets will attract each other.

Which i in row C?

closed choice

grade3

social science

geography

Geography

Use a letter-number grid

A grid is made up of lines of squares. They are organized in rows and columns. A grid can help you use a map. A row is a line of squares that goes from side to side. Rows are marked with letters. A column is a line of squares that goes up and down. Columns are marked with numbers.

The school is in row C.

What can happen to the spores after they are released?

This diagram shows the life cycle of a moss.

closed choice

grade7

natural science

biology

Plant reproduction

Moss and fern life cycles

Moss plants reproduce using both asexual reproduction and sexual reproduction. Moss plants use their male and female parts for sexual reproduction. The male parts produce sperm. Moss live in damp environments, and moss sperm can travel through water to the female parts. The sperm fuse with eggs in the female part. This is called fertilization. Self-fertilization happens when a sperm from a moss plant fertilizes an egg from the same plant. Cross-fertilization happens when a sperm from one moss plant fertilizes an egg from a different moss plant. The fertilized egg grows into a thin brown stalk on top of the female part. Each stalk has a small spore capsule at the top. Moss plants use asexual reproduction to make small spores in the capsules. When the capsules open, the spores are released. When the spores land on the ground, they may germinate and grow into a new moss plant. This new moss plant can produce eggs and sperm and begin the moss life cycle again.

After they are released, spores can land on the ground and germinate. When spores germinate, they grow into adult moss plants. Unlike sperm and eggs, spores do not fuse.

Is the following statement about our solar system true or false? The largest planet is made mainly of ice.

Use the data to answer the question below.

true-or false

grade6

natural science

earth-science

Astronomy

Analyze data to compare properties of planets

A planet's volume tells you the size of the planet. The primary composition of a planet is what the planet is made mainly of. In our solar system, planets are made mainly of rock, gas, or ice.

The table tells you that Jupiter is the largest planet and that Jupiter is made mainly of gas. So, the largest planet is made mainly of gas.

Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

closed choice

grade8

natural science

physics

Particle motion and energy

Identify how particle motion affects temperature and pressure

The temperature of a substance depends on the average kinetic energy of the particles in the substance. The higher the average kinetic energy of the particles, the higher the temperature of the substance. The kinetic energy of a particle is determined by its mass and speed. For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.

Each particle in sample A has more mass than each particle in sample B. The particles in sample A also have a higher average speed than the particles in sample B. So, the particles in sample A have a higher average kinetic energy than the particles in sample B. Because the particles in sample A have the higher average kinetic energy, sample A must have the higher temperature.

Select the organism in the same species as the North American beaver.

This organism is a North American beaver. Its scientific name is Castor canadensis.

closed choice

grade8

natural science

biology

Classification and scientific names

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words. The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits. A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus. Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus. Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

A North American beaver's scientific name is Castor canadensis. Polysticta stelleri does not have the same scientific name as a North American beaver. So, Castor canadensis and Polysticta stelleri are not in the same species. Castor canadensis is in the same genus as Castor fiber, but they are not in the same species. Organisms in the same species have the same scientific names. Castor canadensis and Castor fiber are different species within the same genus. Castor canadensis has the same scientific name as a North American beaver. So, these organisms are in the same species.

Select the organism in the same genus as the western crowned pigeon.

This organism is a western crowned pigeon. Its scientific name is Goura cristata.

closed choice

grade5

natural science

biology

Scientific names

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words. The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits. A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus. Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus. Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

A western crowned pigeon's scientific name is Goura cristata. The first word of its scientific name is Goura. Hystrix cristata and Goura cristata are not in the same genus. These organisms are not in the same genus, but part of their scientific names is the same. Hystrix cristata and Goura cristata have the same species name within their genus, cristata. But the first words of their scientific names are different. Hystrix cristata is in the genus Hystrix, and Goura cristata is in the genus Goura. Lonicera japonica is in the genus Lonicera. The first word of its scientific name is Lonicera. So, Lonicera japonica and Goura cristata are not in the same genus. This organism and the western crowned pigeon are in the same genus and the same species! Both organisms have the same scientific name, Goura cristata.

Which of these states is farthest west?

closed choice

grade2

social science

geography

Geography

Read a map: cardinal directions

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west. A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction. The north arrow points to the North Pole. On most maps, north is at the top of the map.

To find the answer, look at the compass rose. Look at which way the west arrow is pointing. Kentucky is farthest west.

Select the amphibian below.

Amphibians have moist skin and begin their lives in water. A European green toad is an example of an amphibian.

closed choice

grade3

natural science

biology

Classification

Identify mammals, birds, fish, reptiles, and amphibians

Birds, mammals, fish, reptiles, and amphibians are groups of animals. The animals in each group have traits in common. Scientists sort animals into groups based on traits they have in common. This process is called classification.

An African bullfrog 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 barn owl is a bird. It has feathers, two wings, and a beak. Barn owls live on every continent except Antarctica.

Which ocean is highlighted?

closed choice

grade6

social science

geography

Physical Geography

Oceans and continents

Oceans are huge bodies of salt water. The world has five oceans. All of the oceans are connected, making one world ocean.

This is the Pacific Ocean.

Which specific humidity level was measured within the outlined area shown?

The map below shows humidity in the lower atmosphere on April 9, 2016. The map shows specific humidity, a measurement of the amount of water vapor in the air. The outlined area shows an air mass that influenced weather in Africa on that day. Look at the map. Then, answer the question below. Data source: United States National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Physical Sciences Division

closed choice

grade7

natural science

earth-science

Weather and climate

Identify and compare air masses

To study air masses, scientists can use maps that show conditions within Earth's atmosphere. For example, the map below uses color to show specific humidity, a measurement of the amount of water vapor in the air. The map's legend tells you the specific humidity level that each color represents. Colors on the left in the legend represent lower specific humidity levels than colors on the right. For example, areas on the map that are the darkest shade of purple have a specific humidity from zero grams per kilogram (g/kg) up to two g/kg. Areas that are the next darkest shade of purple have a specific humidity from two g/kg up to four g/kg.

Look at the colors shown within the outlined area. Then, use the legend to determine which specific humidity levels those colors represent. The legend tells you that this air mass contained air with specific humidity levels between 20 and 24 grams of water vapor per kilogram of air. 22 grams of water vapor per kilogram of air is within this range. 11 and 16 grams of water vapor per kilogram of air are outside of this range.

Will these magnets attract or repel each other?

Two magnets are placed as shown.

closed choice

grade5

natural science

physics

Magnets

Identify magnets that attract or repel

Magnets can pull or push on other magnets without touching them. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes are called magnetic forces. Magnetic forces are strongest at the magnets' poles, or ends. Every magnet has two poles: a north pole (N) and a south pole (S). Here are some examples of magnets. Their poles are shown in different colors and labeled. Whether a magnet attracts or repels other magnets depends on the positions of its poles. If opposite poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same, or like, poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

To predict if these magnets will attract or repel, look at which poles are closest to each other. The south pole of one magnet is closest to the south pole of the other magnet. Like poles repel. So, these magnets will repel each other.

Which bird's beak is also adapted to get nectar out of long flowers?

Purple honeycreepers live in the forests of South America. The shape of the 's beak is adapted to get nectar out of long flowers. Figure: purple honeycreeper.

closed choice

grade4

natural science

biology

Adaptations

Animal adaptations: beaks, mouths, and necks

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors. The shape of a bird's beak is one example of an adaptation. Birds' beaks can be adapted in different ways. For example, a sharp hooked beak might help a bird tear through meat easily. A short, thick beak might help a bird break through a seed's hard shell. Birds that eat similar food often have similar beaks.

Look at the picture of the purple honeycreeper. The purple honeycreeper has a long, thin beak. Its beak is adapted to get nectar out of long flowers. The purple honeycreeper's long, thin beak can reach deep into the flowers. Now look at each bird. Figure out which bird has a similar adaptation. The green violetear has a long, thin beak. Its beak is adapted to get nectar out of long flowers. The common nighthawk has a short, thin beak. Its beak is not adapted to get nectar out of long flowers. The common nighthawk uses its beak to eat insects and other small invertebrates.

Is the following statement about our solar system true or false? The four largest planets are made mainly of gas or ice.

Use the data to answer the question below.

true-or false

grade8

natural science

earth-science

Astronomy

Analyze data to compare properties of planets

A planet's volume tells you the size of the planet. The primary composition of a planet is what the planet is made mainly of. In our solar system, planets are made mainly of rock, gas, or ice. The volume of a planet is a very large quantity. Large quantities such as this are often written in scientific notation. For example, the volume of Jupiter is 1,430,000,000,000,000 km^3. In scientific notation, Jupiter's volume is written as 1.43 x 10^15 km^3. To compare two numbers written in scientific notation, compare their exponents. The bigger the exponent is, the bigger the number is. For example: 1.43 x 10^15 is larger than 1.43 x 10^12 If their exponents are equal, compare the first numbers. For example: 1.43 x 10^15 is larger than 1.25 x 10^15

To decide which four planets are the largest, look at the volumes and compare the exponents. The volumes of Jupiter, Saturn, Uranus, and Neptune have the largest exponents. So, these four planets are the largest. Jupiter and Saturn are made mainly of gas. Uranus and Neptune are made mainly of ice. So, the four largest planets are made mainly of gas or ice.

Which is this organism's scientific name?

This organism is a goldfish. It is also called Carassius auratus.

closed choice

grade5

natural science

biology

Scientific names

Identify common and scientific names

An organism's common name is the name that people normally call the organism. Common names often contain words you know. An organism's scientific name is the name scientists use to identify the organism. Scientific names often contain words that are not used in everyday English. Scientific names are written in italics, but common names are usually not. The first word of the scientific name is capitalized, and the second word is not. For example, the common name of the animal below is giant panda. Its scientific name is Ailuropoda melanoleuca.

Carassius auratus is written in italics. The first word is capitalized, and the second word is not. So, Carassius auratus is the scientific name.

Which i in row A?

closed choice

grade3

social science

geography

Geography

Use a letter-number grid

A grid is made up of lines of squares. They are organized in rows and columns. A grid can help you use a map. A row is a line of squares that goes from side to side. Rows are marked with letters. A column is a line of squares that goes up and down. Columns are marked with numbers.

The police department is in row A.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different sizes.

closed choice

grade6

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by using magnets of different sizes. The magnitude of the magnetic force is smaller when the magnets are smaller.

The magnets in Pair 1 attract. The magnets in Pair 2 repel. But whether the magnets attract or repel affects only the direction of the magnetic force. It does not affect the magnitude of the magnetic force. Magnet sizes affect the magnitude of the magnetic force. Imagine magnets that are the same shape and made of the same material. The smaller the magnets, the smaller the magnitude of the magnetic force between them. Magnet A is the same size in both pairs. But Magnet B is smaller in Pair 2 than in Pair 1. So, the magnitude of the magnetic force is smaller in Pair 2 than in Pair 1.

Select the organism in the same genus as the small-mouth salamander.

This organism is a small-mouth salamander. Its scientific name is Ambystoma texanum.

closed choice

grade8

natural science

biology

Classification and scientific names

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words. The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits. A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus. Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus. Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

A small-mouth salamander's scientific name is Ambystoma texanum. The first word of its scientific name is Ambystoma. Lissotriton helveticus is in the genus Lissotriton. The first word of its scientific name is Lissotriton. So, Lissotriton helveticus and Ambystoma texanum are not in the same genus. This organism and the small-mouth salamander are in the same genus and the same species! Both organisms have the same scientific name, Ambystoma texanum. Lissotriton vulgaris is in the genus Lissotriton. The first word of its scientific name is Lissotriton. So, Lissotriton vulgaris and Ambystoma texanum are not in the same genus.

Which of these states is farthest east?

closed choice

grade5

social science

geography

Maps

Read a map: cardinal directions

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west. A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction. The north arrow points to the North Pole. On most maps, north is at the top of the map.

To find the answer, look at the compass rose. Look at which way the east arrow is pointing. Maine is farthest east.

Which property do these four objects have in common?

Select the best answer.

closed choice

grade5

natural science

physics

Materials

Compare properties of objects

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it. Different objects can have properties in common. You can use these properties to put objects into groups. Grouping objects by their properties is called classification.

Look at each object. For each object, decide if it has that property. A slippery object is hard to hold onto or stand on. The yarn pom pom and the tennis ball are not slippery. A fuzzy object is covered in soft hair. All four objects are fuzzy. A stretchy object gets longer when you pull on it. The socks are stretchy, but the kiwi is not. The property that all four objects have in common is fuzzy.

Is the following statement about our solar system true or false? The four largest planets are made mainly of gas or ice.

Use the data to answer the question below.

true-or false

grade8

natural science

earth-science

Astronomy

Analyze data to compare properties of planets

A planet's volume tells you the size of the planet. The primary composition of a planet is what the planet is made mainly of. In our solar system, planets are made mainly of rock, gas, or ice. The volume of a planet is a very large quantity. Large quantities such as this are often written in scientific notation. For example, the volume of Jupiter is 1,430,000,000,000,000 km^3. In scientific notation, Jupiter's volume is written as 1.43 x 10^15 km^3. To compare two numbers written in scientific notation, compare their exponents. The bigger the exponent is, the bigger the number is. For example: 1.43 x 10^15 is larger than 1.43 x 10^12 If their exponents are equal, compare the first numbers. For example: 1.43 x 10^15 is larger than 1.25 x 10^15

To decide which four planets are the largest, look at the volumes and compare the exponents. The volumes of Jupiter, Saturn, Uranus, and Neptune have the largest exponents. So, these four planets are the largest. Jupiter and Saturn are made mainly of gas. Uranus and Neptune are made mainly of ice. So, the four largest planets are made mainly of gas or ice.

Which of these states is farthest south?

closed choice

grade2

social science

geography

Geography

Read a map: cardinal directions

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west. A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction. The north arrow points to the North Pole. On most maps, north is at the top of the map.

To find the answer, look at the compass rose. Look at which way the south arrow is pointing. Ohio is farthest south.

Which air temperature was measured within the outlined area shown?

The map below shows air temperatures in the lower atmosphere on April 19, 2016. The outlined area shows an air mass that influenced weather in North America on that day. Look at the map. Then, answer the question below. Data source: United States National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Physical Sciences Division

closed choice

grade6

natural science

earth-science

Weather and climate

Identify and compare air masses

To study air masses, scientists can use maps that show conditions within Earth's atmosphere. For example, the map below uses color to show air temperatures. The map's legend tells you the temperature that each color represents. Colors on the left in the legend represent lower temperatures than colors on the right. For example, areas on the map that are the darkest shade of blue have a temperature from -25°C up to -20°C. Areas that are the next darkest shade of blue have a temperature from -20°C up to -15°C.

Look at the colors shown within the outlined area. Then, use the legend to determine which air temperatures those colors represent. 15°C. -17°C is within this range. -4°C and 3°C are outside of this range.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

closed choice

grade5

natural science

physics

Magnets

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by changing the distance between them. The magnitude of the magnetic force is smaller when there is a greater distance between the magnets.

The magnets in Pair 1 attract. The magnets in Pair 2 repel. But whether the magnets attract or repel affects only the direction of the magnetic force. It does not affect the magnitude of the magnetic force. Distance affects the magnitude of the magnetic force. When there is a greater distance between magnets, the magnitude of the magnetic force between them is smaller. There is a greater distance between the magnets in Pair 2 than in Pair 1. So, the magnitude of the magnetic force is smaller in Pair 2 than in Pair 1.

Which of these continents does the prime meridian intersect?

closed choice

grade5

social science

geography

Maps

Use lines of latitude and longitude

Lines of latitude and lines of longitude are imaginary lines drawn on some globes and maps. They can help you find places on globes and maps. Lines of latitude show how far north or south a place is. We use units called degrees to describe how far a place is from the equator. The equator is the line located at 0° latitude. We start counting degrees from there. Lines north of the equator are labeled N for north. Lines south of the equator are labeled S for south. Lines of latitude are also called parallels because each line is parallel to the equator. Lines of longitude are also called meridians. They show how far east or west a place is. We use degrees to help describe how far a place is from the prime meridian. The prime meridian is the line located at 0° longitude. Lines west of the prime meridian are labeled W. Lines east of the prime meridian are labeled E. Meridians meet at the north and south poles. The equator goes all the way around the earth, but the prime meridian is different. It only goes from the North Pole to the South Pole on one side of the earth. On the opposite side of the globe is another special meridian. It is labeled both 180°E and 180°W. Together, lines of latitude and lines of longitude form a grid. You can use this grid to find the exact location of a place.

The prime meridian is the line at 0° longitude. It intersects Africa. It does not intersect South America or Asia.

What is the expected ratio of offspring with green body feathers to offspring with blue body feathers? Choose the most likely ratio.

In a group of budgerigar parakeets, some individuals have green body feathers and others have blue body feathers. In this group, the gene for the body feather color trait has two alleles. The allele for blue body feathers (b) is recessive to the allele for green body feathers (B). This Punnett square shows a cross between two budgerigar parakeets.

closed choice

grade8

natural science

biology

Genes to traits

Use Punnett squares to calculate ratios of offspring types

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 green body feathers or blue body feathers, consider whether each phenotype is the dominant or recessive allele's version of the body feather color trait. The question tells you that the b allele, which is for blue body feathers, is recessive to the B allele, which is for green body feathers. Green body feathers is the dominant allele's version of the body feather color trait. A budgerigar parakeet with the dominant version of the body feather color trait must have at least one dominant allele for the body feather color gene. So, offspring with green body feathers must have the genotype BB or Bb. There are 2 boxes in the Punnett square with the genotype BB or Bb. These boxes are highlighted below. Blue body feathers is the recessive allele's version of the body feather color trait. A budgerigar parakeet with the recessive version of the body feather color trait must have only recessive alleles for the body feather color gene. So, offspring with blue body feathers must have the genotype bb. There are 2 boxes in the Punnett square with the genotype bb. These boxes are highlighted below. So, the expected ratio of offspring with green body feathers to offspring with blue body feathers is 2:2. This means that, on average, this cross will produce 2 offspring with green body feathers for every 2 offspring with blue body feathers.

Which continent is highlighted?

closed choice

grade7

social science

geography

Physical Geography

Oceans and continents

A continent is one of the major land masses on the earth. Most people say there are seven continents.

This continent is South America.

Will these magnets attract or repel each other?

Two magnets are placed as shown.

closed choice

grade4

natural science

physics

Magnets

Identify magnets that attract or repel

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles: north and south. Here are some examples of magnets. The north pole of each magnet is labeled N, and the south pole is labeled S. If opposite poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same, or like, poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

To predict if these magnets will attract or repel, look at which poles are closest to each other. Both poles of each magnet line up with both poles of the other magnet. The south pole of each magnet is closest to the north pole of the other magnet. Opposite poles attract. So, these magnets will attract each other.

Will these magnets attract or repel each other?

Two magnets are placed as shown. Hint: Magnets that attract pull together. Magnets that repel push apart.

closed choice

grade2

natural science

physics

Magnets

Identify magnets that attract or repel

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles, called north and south. Here are some examples of magnets. The north pole of each magnet is marked N, and the south pole is marked S. If different poles are closest to each other, the magnets attract. The magnets in the pair below attract. If the same poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

Will these magnets attract or repel? To find out, look at which poles are closest to each other. The south pole of one magnet is closest to the north pole of the other magnet. Poles that are different attract. So, these magnets will attract each other.

Which solution has a higher concentration of blue particles?

The diagram below is a model of two solutions. Each blue ball represents one particle of solute.

closed choice

grade8

natural science

chemistry

Solutions

Compare concentrations of solutions

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent. The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent. concentration = particles of solute / volume of solvent

In Solution A and Solution B, the blue particles represent the solute. To figure out which solution has a higher concentration of blue particles, look at both the number of blue particles and the volume of the solvent in each container. Use the concentration formula to find the number of blue particles per milliliter. Solution B has more blue particles per milliliter. So, Solution B has a higher concentration of blue particles.

Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

closed choice

grade7

natural science

physics

Velocity, acceleration, and forces

Compare magnitudes of magnetic forces

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces. The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other. You can change the magnitude of a magnetic force between two magnets by changing the distance between them. The magnitude of the magnetic force is greater when there is a smaller distance between the magnets.

The magnets in Pair 2 attract. The magnets in Pair 1 repel. But whether the magnets attract or repel affects only the direction of the magnetic force. It does not affect the magnitude of the magnetic force. Distance affects the magnitude of the magnetic force. When there is a smaller distance between magnets, the magnitude of the magnetic force between them is greater. There is a smaller distance between the magnets in Pair 1 than in Pair 2. So, the magnitude of the magnetic force is greater in Pair 1 than in Pair 2.

Which continent is highlighted?

closed choice

grade8

social science

geography

Physical Geography

Oceans and continents

A continent is one of the major land masses on the earth. Most people say there are seven continents.

This continent is Asia.

Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

closed choice

grade6

natural science

physics

Particle motion and energy

Identify how particle motion affects temperature and pressure

The temperature of a substance depends on the average kinetic energy of the particles in the substance. The higher the average kinetic energy of the particles, the higher the temperature of the substance. The kinetic energy of a particle is determined by its mass and speed. For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.

The particles in both samples have the same average speed, but each particle in sample B has more mass than each particle in sample A. So, the particles in sample B have a higher average kinetic energy than the particles in sample A. Because the particles in sample B have the higher average kinetic energy, sample B must have the higher temperature.

Based on the event chain, which event leads directly to the defeat of the loon's team?

This event chain shows the events from an Ojibwe legend.

closed choice

grade6

language science

writing-strategies

Visual elements

Read graphic organizers

A graphic organizer is a chart or picture that shows how ideas, facts, or topics are related to one another. When you read, look for graphic organizers included in the text. You can use these images to find key information. You can also create your own graphic organizers with information that you've read. Doing this can help you think about the ideas in the text and easily review them. When you write, you can use graphic organizers to organize your thoughts and plan your writing.

An event chain uses arrows to show the order of events. This event chain shows the events from an Ojibwe legend. Follow the arrows to see the order of events. Find the box that says The loon's team is quickly defeated. The event The Winter Wind comes and joins the hawk's team comes directly before this in the event chain. This tells you that the event The Winter Wind joins the hawk's team directly leads to the defeat of the loon's team.