Question: Select the reptile below.

Choices:
- green tree frog
- box turtle

Reptiles have scaly, waterproof skin. Most reptiles live on land. A dwarf crocodile is an example of a reptile.

natural science

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.

Solution:
A box turtle is a reptile. It has scaly, waterproof skin.
Box turtles can live to be over 100 years old!
A green tree frog is an amphibian. It has moist skin and begins its life in water.
There are many kinds of tree frogs. Most tree frogs are very small. They can walk on thin branches.


Question: Which ocean is highlighted?

Choices:
- the Atlantic Ocean
- the Indian Ocean
- the Pacific Ocean
- the Southern Ocean

social science

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

Solution: This is the Pacific Ocean.


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

Choices:
- the surroundings . . . each cake
- each cake . . . the surroundings

Keenan baked two identical cakes. When he took them out of the oven, he left one cake in its pan and took the other cake out of its pan to put it on a plate. This table shows how the temperature of each cake changed over 5minutes.

natural science

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.

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


Question: Which of these cities is marked on the map?

Choices:
- Las Vegas
- San Francisco
- Phoenix
- Salt Lake City

social science

Solution: The city is Las Vegas, Nevada. Salt Lake City, Phoenix, and San Francisco are marked with gray circles on the map below.


Question:
Is the following statement about our solar system true or false?
Earth's volume is more than ten times as great as Mars's volume.

Choices:
- false
- true

Use the data to answer the question below.

natural science

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, first 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 multiply a number written in scientific notation by a power of 10, write the multiple of 10 as 10 raised to an exponent. Then, add the exponents. For example:
1.43 x 10^15 · 1000
= 1.43 x 10^15 · 10^3
= 1.43 x 10^(15 + 3)
= 1.43 x 10^18

Solution:
To determine if this statement is true, calculate the value of ten times the volume of Mars.
Then compare the result to the volume of Earth. The volume of Earth is 1.08 x 10^12 km^3, which is less than 1.63 x 10^12 km^3. So, Earth's volume is less than ten times as great as Mars's volume.


Question: Which is the main persuasive appeal used in this ad?

Choices:
- logos (reason)
- pathos (emotion)
- ethos (character)

language science

Identify appeals to ethos, pathos, and logos in advertisements

The purpose of an advertisement is to persuade people to do something. To accomplish this purpose, advertisements use three types of persuasive strategies, or appeals:
Appeals to ethos, or character, show that the writer or speaker is trustworthy or is an authority on a subject. An ad that appeals to ethos might do one of the following:
say that a brand has been trusted for many years
note that a brand is recommended by a respected organization or celebrity
include a quote from a "real person" who shares the audience's values
Appeals to logos, or reason, use logic and specific evidence. An ad that appeals to logos might do one of the following:
use graphs or charts to display information
mention the results of scientific studies
explain the science behind a product or service
Appeals to pathos, or emotion, use feelings rather than facts to persuade the audience. An ad that appeals to pathos might do one of the following:
trigger a fear, such as the fear of embarrassment
appeal to a desire, such as the desire to appear attractive
link the product to a positive feeling, such as adventure, love, or luxury

Solution: The ad appeals to pathos, or emotion. It links the product to feelings of happiness.


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

Choices:
- sample A
- sample B
- neither; the samples have the same 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.

natural science

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.

Solution:
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.


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

Choices:
- silver maple
- beaver
- gray fox
- pine vole

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

natural science

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.

Solution:
Producers do not eat other organisms. So, in a food web, producers do not have arrows pointing to them from other organisms.
The persimmon tree does not have any arrows pointing to it. So, the persimmon tree is a producer.
The gray fox has arrows pointing to it, so it is not a producer.
The silver maple does not have any arrows pointing to it. So, the silver maple is a producer.
The beaver has an arrow pointing to it, so it is not a producer.
The pine vole has arrows pointing to it, so it is not a producer.


Question: Which type of force from the student's finger presses the key on the keyboard?

Choices:
- push
- pull

A student types on a keyboard. Her finger applies a force to a key.

natural science

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.

Solution: The student's finger applies a force to the key as she types. The direction of this force is away from her finger. This force is a push.


Question: What is the capital of Ohio?

Choices:
- Lincoln
- Columbus
- Chicago
- Jefferson City

social science

Solution: Columbus is the capital of Ohio.


Question: What can Terrell and Allie trade to each get what they want?

Choices:
- Terrell can trade his tomatoes for Allie's carrots.
- Allie can trade her broccoli for Terrell's oranges.
- Allie can trade her almonds for Terrell's tomatoes.
- Terrell can trade his tomatoes for Allie's broccoli.

Trade happens when people agree to exchange goods and services. People give up something to get something else. Sometimes people barter, or directly exchange one good or service for another.
Terrell and Allie open their lunch boxes in the school cafeteria. Neither Terrell nor Allie got everything that they wanted. The table below shows which items they each wanted:

Look at the images of their lunches. Then answer the question below.
Terrell's lunch Allie's lunch

social science

Solution:
Look at the table and images.
Terrell wants broccoli. Allie wants tomatoes. They can trade tomatoes for broccoli to both get what they want. Trading other things would not help both people get more items they want.


Question: Which animal's feet are also adapted for swimming?

Choices:
- European beaver
- sable

Black-bellied whistling ducks live near lakes and streams in North America. They find most of their food in shallow water. The feet of the  are adapted for swimming.
Figure: black-bellied whistling duck.

natural science

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.

Solution:
Look at the picture of the black-bellied whistling duck.
The black-bellied whistling duck has webbed feet. Its feet are adapted for swimming. As it swims, the black-bellied whistling duck uses its webbed feet to push itself through water.
Now look at each animal. Figure out which animal has a similar adaptation.
The European beaver has webbed feet. Its feet are adapted for swimming.
The sable has hoofed feet. Its feet are not adapted for swimming. The sable uses its feet to walk and run on hard ground.


Question: What is the capital of Massachusetts?

Choices:
- Boston
- Chicago
- Cambridge
- Concord

social science

Identify state capitals of the Northeast

Solution: Boston is the capital of Massachusetts.


Question: What is the capital of South Dakota?

Choices:
- Saint Paul
- Madison
- Pierre
- Rapid City

social science

Solution: Pierre is the capital of South Dakota.


Question: Identify the question that Natalie's experiment can best answer.

Choices:
- Does fabric turn darker when soaked in a mixture of black dye and water for 15 minutes compared to 30 minutes?
- Does linen fabric turn darker than cotton fabric when soaked in a mixture of black dye and water?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Natalie prepared ten buckets, each with one gallon of boiling water and three tablespoons of black fabric dye. Natalie soaked white linen fabric squares in five of the buckets, and white cotton fabric squares in the other five buckets. All of the fabric squares were soaked for 15 minutes. After the fabric dried, Natalie scored the darkness of the squares on a scale from light to dark. She compared the darkness of the linen fabric to the darkness of the cotton fabric.
Figure: fabric that has been dyed black.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: Which animal's neck is also adapted for hunting prey while keeping the rest of its body still?

Choices:
- mallard
- painted stork

Great egrets live near wetlands and lakes. They eat mostly fish.
The 's neck helps it grab fish while keeping the rest of its body still. If the egret had to move its body, it might scare the fish away.
Figure: great egret.

natural science

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 an animal's neck is one example of an adaptation. Animals' necks can be adapted in different ways. For example, a large frilled neck might help an animal appear dangerous to its predators. A long neck might help an animal get food from tall trees.

Solution:
Look at the picture of the great egret.
The great egret has a long neck. Its neck is adapted for hunting prey while keeping the rest of its body still. This allows the great egret to grab the prey without scaring it away.
Now look at each animal. Figure out which animal has a similar adaptation.
The painted stork has a long neck. Its neck is adapted for hunting prey while keeping the rest of its body still.
The mallard has a short neck. Its neck is not adapted for hunting prey while keeping the rest of its body still.


Question: Does this passage describe the weather or the climate?

Choices:
- climate
- weather

Figure: Madison, Wisconsin.
Madison, the capital of Wisconsin, is located in the southern part of the state. For two weeks in December, the temperature never rose above 20°F.
Hint: Weather is what the atmosphere is like at a certain place and time. Climate is the pattern of weather in a certain place.

natural science

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.

Solution:
Read the passage carefully.
Madison, the capital of Wisconsin, is located in the southern part of the state. For two weeks in December, the temperature never rose above 20°F.
The underlined part of the passage tells you what the temperature in Madison was like in December. This passage describes the atmosphere at a certain place and time. So, this passage describes the weather.


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

Choices:
- The magnitude of the magnetic force is the same in both pairs.
- The magnitude of the magnetic force is smaller in Pair 2.
- The magnitude of the magnetic force is smaller in Pair 1.

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.

natural science

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.

Solution:
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.
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.


Question: Select the organism in the same species as the American alligator.

Choices:
- Alligator sinensis
- Alligator mississippiensis
- Aequorea victoria

This organism is an American alligator. Its scientific name is Alligator mississippiensis.

natural science

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.

Solution:
An American alligator's scientific name is Alligator mississippiensis.
Aequorea victoria does not have the same scientific name as an American alligator. So, Alligator mississippiensis and Aequorea victoria are not in the same species.
Alligator mississippiensis is in the same genus as Alligator sinensis, but they are not in the same species.
Organisms in the same species have the same scientific names. Alligator mississippiensis and Alligator sinensis are different species within the same genus.
Alligator mississippiensis has the same scientific name as an American alligator. So, these organisms are in the same species.


Question: Which property matches this object?

Choices:
- bouncy
- opaque

natural science

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.

Solution:
Look at the object.
Think about each property.
A bouncy object will bounce back from the floor if you drop it. The tin foil is not bouncy.
An opaque object does not let light through. The tin foil is opaque.


Question: What is the capital of Montana?

Choices:
- Helena
- Birmingham
- Tucson
- Salem

social science

Solution: Helena is the capital of Montana.


Question: Which property do these four objects have in common?

Choices:
- sticky
- translucent
- sweet

natural science

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.

Solution:
Look at each object.
For each object, decide if it has that property.
A translucent object lets light through. But you cannot see clearly through a translucent object. All four objects are translucent.
A sticky object can attach or stick to other things. The honey is sticky, but the marbles are not.
Sugar has a sweet taste. The honey is sweet, but the wet ice cube and the marbles are not.
The property that all four objects have in common is translucent.


Question: What is the capital of Georgia?

Choices:
- Savannah
- Athens
- Atlanta
- Boston

social science

Identify state capitals of the Southeast

Solution: Atlanta is the capital of Georgia.


Question: Which material is these swim goggles made of?

Choices:
- wool
- plastic

natural science

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.

Solution:
Look at the picture of the swim goggles.
The swim goggles are made of two different materials. The lenses are plastic, and the straps are rubber.


Question:
Complete the statement.
Ethanol is ().

Choices:
- an elementary substance
- a compound

The model below represents a molecule of ethanol. Ethanol can be used as a fuel. Most of the gasoline that is used in the United States is about 10% ethanol.

natural science

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 boron is B, and the atomic symbol for the chemical element chlorine is Cl.
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 a molecule of the compound boron trichloride.
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.

Solution:
Use the model to determine whether ethanol 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 a molecule of ethanol is composed of six hydrogen atoms, two carbon atoms, and one oxygen atom bonded together.
Step 2: Determine whether the substance is an elementary substance or a compound.
You know from Step 1 that ethanol is composed of three chemical elements: hydrogen, carbon, and oxygen. Since ethanol is composed of multiple chemical elements bonded together, ethanol is a compound.


Question: Which of these cities is marked on the map?

Choices:
- San Antonio
- Boston
- Washington, D.C.
- Atlanta

social science

Solution: The city is Washington, D.C. San Antonio, Boston, and Atlanta are marked with gray circles on the map below.


Question: Select the organism in the same genus as the North American beaver.

Choices:
- Castor canadensis
- Ovis canadensis
- Strix varia

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

natural science

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.

Solution:
A North American beaver's scientific name is Castor canadensis. The first word of its scientific name is Castor.
This organism and the North American beaver are in the same genus and the same species! Both organisms have the same scientific name, Castor canadensis.
Strix varia is in the genus Strix. The first word of its scientific name is Strix. So, Strix varia and Castor canadensis are not in the same genus.
Ovis canadensis and Castor canadensis are not in the same genus.
These organisms are not in the same genus, but part of their scientific names is the same. Ovis canadensis and Castor canadensis have the same species name within their genus, canadensis. But the first words of their scientific names are different. Ovis canadensis is in the genus Ovis, and Castor canadensis is in the genus Castor.


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

Choices:
- neither; the samples have the same temperature
- sample B
- sample A

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.

natural science

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.

Solution:
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.


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

Choices:
- each refrigerator . . . the surroundings
- the surroundings . . . each refrigerator

Two identical refrigerators in a restaurant kitchen lost power. The door of one fridge was slightly open, and the door of the other fridge was closed. This table shows how the temperature of each refrigerator changed over 10minutes.

natural science

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.

Solution: The temperature of each refrigerator increased, which means that the thermal energy of each refrigerator increased. So, thermal energy was transferred from the surroundings to each refrigerator.


Question: Select the fish below.

Choices:
- tiger shark
- leaf-tailed gecko
- Hermann's tortoise
- dwarf crocodile

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

natural science

Identify mammals, birds, fish, reptiles, and amphibians

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

Solution:
A tiger shark is a fish. It lives underwater. It has fins, not limbs.
Tiger sharks are nocturnal. This means that they are active mostly at night.
A leaf-tailed gecko is a reptile. It has scaly, waterproof skin.
Many geckos have special pads on their toes. The pads help them climb up plants and rocks.
A dwarf crocodile is a reptile. It has scaly, waterproof skin.
Crocodiles hunt their prey in or near water.
A Hermann's tortoise is a reptile. It has scaly, waterproof skin.
A tortoise's shell protects it from predators. When a tortoise feels threatened, it can pull its head and legs inside its shell.


Question: Select the chemical formula for this molecule.

Choices:
- BF3
- BFe3
- HB3F
- B2F3

natural science

Match chemical formulas to 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.
Notice how each ball is labeled with a symbol made of one or more letters. The symbol is an abbreviation for a chemical element. The ball represents one atom of that element.
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 molecule contains the symbol for each chemical element in the molecule. Many chemical formulas use subscripts. A subscript is text that is smaller and placed lower than the normal line of text.
In chemical formulas, the subscripts are numbers. The subscript is always written after the symbol for an element. The subscript tells you how many atoms that symbol represents. If the symbol represents just one atom, then no subscript is included.
The symbols in the chemical formula for a molecule match the symbols in the ball-and-stick model for that molecule. The ball-and-stick model shown before and the chemical formula shown above represent the same substance.

Solution:
B is the symbol for boron. F is the symbol for fluorine. This ball-and-stick model shows a molecule with one boron atom and three fluorine atoms.
The chemical formula will contain the symbols B and F. There is one boron atom, so B will not have a subscript. There are three fluorine atoms, so F will have a subscript of 3.
The correct formula is BF3.
The diagram below shows how each part of the chemical formula matches with each part of the model above.


Question: Which of the following best describes a population in a forest in the Cascade mountains?

Choices:
- the western red cedar trees
- the great horned owls and the northern pygmy owls
- the Douglas fir trees and the long-eared owls

Read the passage. Then answer the question below.

The forests in Oregon's Cascade mountains include western red cedar and Douglas fir, two of the tallest tree species in the world. Both of these species can grow to be 100 meters tall, or as tall as a 30-story building!
Several owl species, including long-eared owls, great horned owls, and northern pygmy owls, live in these forests. Owls are nocturnal, which means they are most active at night. During the day, they rest high in the tall trees.
Figure: fir trees in the Cascade mountains.

natural science

Describe populations, communities, and ecosystems

In an environment, organisms interact with each other and with their nonliving surroundings. To help describe these interactions, ecologists use specific terms for different types of groups.
A single organism is an individual. Individuals of the same species that live in the same place are part of a population.
Multiple populations of different species that live in the same place are part of a community.
Together, communities of living organisms and the nonliving parts of their environment make up an ecosystem.


Question: Which country is highlighted?

Choices:
- Vanuatu
- the Marshall Islands
- the Federated States of Micronesia
- Solomon Islands

social science

Identify and select countries of Oceania

Solution:
This country is the Marshall Islands.
Does the Marshall Islands have any territorial disputes?
The Marshall Islands claims to own Wake Island, which is a disputed territory. In other words, multiple countries or groups claim that the area rightfully belongs to them.
The United States claimed Wake Island in 1899 and has controlled it since then. But the Marshall Islands considers the island part of its territory. It says that its people have traveled to the island to gather food and resources for many years. Today, the island is mainly used by the U.S. Air Force.


Question: Which of these states is farthest north?

Choices:
- Alabama
- Oklahoma
- Arizona
- West Virginia

social science

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.

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


Question: Based on the text, what was one of the things that made Alex different from most parrots?

Choices:
- He loved playing with blocks.
- He was an African grey parrot.
- He was able to do math.

Read the text about Alex the parrot.
Most parrots can speak, or at least copy the sounds of people talking. Alex, an African grey parrot, learned to do much more. He knew how to do simple math. In fact, he was capable of adding up to six objects. Alex added up crackers, jelly beans, and blocks. He could also point out seven different colors and six shapes. And he knew more than a hundred words!
Alex's owner taught him for more than thirty years and observed a lot about how parrots learn. People had worked with animals before Alex to see if animals could understand language and math. But Alex proved that animals might be even smarter than we thought!

language science

Solution:
Look at the text in bold below. It tells you what made Alex different from most parrots.
Most parrots can speak, or at least copy the sounds of people talking. Alex, an African grey parrot, learned to do much more. He knew how to do simple math. In fact, he was capable of adding up to six objects. Alex added up crackers, jelly beans, and blocks. He could also point out seven different colors and six shapes. And he knew more than a hundred words!


Question: What can Emmet and Kathleen trade to each get what they want?

Choices:
- Emmet can trade his tomatoes for Kathleen's broccoli.
- Emmet can trade his tomatoes for Kathleen's sandwich.
- Kathleen can trade her almonds for Emmet's tomatoes.
- Kathleen can trade her broccoli for Emmet's oranges.

Trade happens when people agree to exchange goods and services. People give up something to get something else. Sometimes people barter, or directly exchange one good or service for another.
Emmet and Kathleen open their lunch boxes in the school cafeteria. Both of them could be happier with their lunches. Emmet wanted broccoli in his lunch and Kathleen was hoping for tomatoes. Look at the images of their lunches. Then answer the question below.

social science

Solution:
Emmet wanted broccoli in his lunch and Kathleen was hoping for tomatoes. Look at the labeled part of the images.
Emmet has tomatoes. Kathleen has broccoli. They can trade tomatoes for broccoli to both be happier. Trading other things would not help either person get more items they want.


Question: Look at the picture. Which word best describes the sound this lion makes?

Choices:
- roaring
- splashing
- banging

language science

Choose the sensory details that match the picture

When you write, you can use sensory details. These sense words help your reader understand what something looks, sounds, tastes, smells, or feels like.
Sensory Category | Description
Sight | These are words like bright, clean, and purple. A reader can imagine looking at these details.
Sound | These are words like hissing, buzzing, and ringing. A reader can imagine hearing these details.
Taste | These are words like juicy, sweet, and burnt. A reader can imagine tasting these details.
Smell | These are words like fruity, sweet, and stinky. A reader can imagine smelling these details.
Touch | These are words like fuzzy, wet, and soft. A reader can imagine feeling these details.
Many sense words can describe more than one sense. For example, soft can describe a touch or a sound. And sweet can describe a taste or a smell.

Solution:
Look at the picture.
The word roaring describes the sound this lion makes.
Splashing and banging can also describe sounds. But they do not describe the sounds this lion makes.


Question:
Complete the text to describe the diagram.
Solute particles moved in both directions across the permeable membrane. But more solute particles moved across the membrane (). When there was an equal concentration on both sides, the particles reached equilibrium.

Choices:
- to the right than to the left
- to the left than to the right

The diagram below shows a solution with one solute. Each solute particle is represented by a pink ball. The solution fills a closed container that is divided in half by a membrane. The membrane, represented by a dotted line, is permeable to the solute particles.
The diagram shows how the solution can change over time during the process of diffusion.

natural science

In a solution, solute particles move and spread throughout the solvent. The diagram below shows how a solution can change over time. Solute particles move from the area where they are at a higher concentration to the area where they are at a lower concentration. This movement happens through the process of diffusion.
As a result of diffusion, the concentration of solute particles becomes equal throughout the solution. When this happens, the solute particles reach equilibrium. At equilibrium, the solute particles do not stop moving. But their concentration throughout the solution stays the same.
Membranes, or thin boundaries, can divide solutions into parts. A membrane is permeable to a solute when particles of the solute can pass through gaps in the membrane. In this case, solute particles can move freely across the membrane from one side to the other.
So, for the solute particles to reach equilibrium, more particles will move across a permeable membrane from the side with a higher concentration of solute particles to the side with a lower concentration. At equilibrium, the concentration on both sides of the membrane is equal.

Solution:
Look at the diagram again. It shows you how the solution changed during the process of diffusion.
Before the solute particles reached equilibrium, there were 6 solute particles on the left side of the membrane and 2 solute particles on the right side of the membrane.
When the solute particles reached equilibrium, there were 4 solute particles on each side of the membrane. There were 2 more solute particles on the right side of the membrane than before.
So, for the solute particles to reach equilibrium, more solute particles must have moved across the membrane to the right than to the left.


Question: Which continent is highlighted?

Choices:
- Antarctica
- Europe
- Asia
- Africa

social science

A continent is one of the seven largest areas of land on earth.

Solution: This continent is Europe.


Question: Identify the question that Farid's experiment can best answer.

Choices:
- Can pennies hold more drops of pure water or water mixed with hand soap?
- Can pennies hold more drops of water mixed with dish soap or water mixed with hand soap?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Farid used a dropper to put equal-sized drops of pure water, one at a time, onto a penny. The drops stayed together and formed a dome on the penny's surface. Farid recorded the number of drops he could add before the water spilled over the edge of the penny. Then, he rinsed and dried the penny, and repeated the test using water mixed with hand soap. He repeated these trials on nine additional pennies. Farid compared the average number of pure water drops to the average number of water drops mixed with hand soap that he could add to a penny before the water spilled over.
Figure: a dome of water on the surface of a penny.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: What is the name of the colony shown?

Choices:
- New Hampshire
- Delaware
- Kentucky
- Wisconsin

social science

Solution: The colony is Delaware.


Question: Will these magnets attract or repel each other?

Choices:
- repel
- attract

natural science

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.

Solution:
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 north pole of the other magnet. Opposite poles attract. So, these magnets will attract each other.


Question: Which statement describes the Steigerwald Forest ecosystem?

Choices:
- It has soil that is rich in nutrients.
- It has a small amount of rain or snow.
- It has soil that is poor in nutrients.

Figure: Steigerwald Forest.
The Steigerwald Forest is a temperate deciduous forest ecosystem in Bavaria, a state in southern Germany. This forest has many oak and beech trees.

natural science

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

Solution: 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, the following statement describes the Steigerwald Forest ecosystem: warm, wet summers and cold, wet winters, soil that is rich in nutrients, and only a few types of trees. It has soil that is rich in nutrients. The following statements do not describe the Steigerwald Forest: warm, wet summers and cold, wet winters, soil that is rich in nutrients, and only a few types of trees. It has soil that is poor in nutrients. It has a small amount of rain or snow.


Question: How much time passed between the founding of Jamestown, Virginia, and the start of the Revolutionary War?

Choices:
- 100 to 150 years
- less than 50 years
- 50 to 100 years
- more than 150 years

Look at the timeline. Then answer the question.

social science

The American Revolution: the Thirteen Colonies under British rule

Solution:
More than 150 years passed between the founding of the Jamestown colony in Virginia and the start of the Revolutionary War.
Jamestown was founded in 1607. The Revolutionary War started 168 years later, in 1775.


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

Choices:
- The magnetic force is stronger in Pair 1.
- The strength of the magnetic force is the same in both pairs.
- The magnetic force is stronger in Pair 2.

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.

natural science

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.

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


Question: Which animal's feet are also adapted for swimming?

Choices:
- New Zealand falcon
- California gull

Red-eared sliders are a type of turtle. They are found in ponds, lakes, and rivers in many parts of North America. The feet of the  are adapted for swimming.
Figure: red-eared slider.

natural science

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.

Solution:
Look at the picture of the red-eared slider.
The red-eared slider has webbed feet. Its feet are adapted for swimming. As it swims, the red-eared slider uses its webbed feet to push itself through water.
Now look at each animal. Figure out which animal has a similar adaptation.
The California gull has small claws and webbed feet. Its feet are adapted for swimming.
The New Zealand falcon has long toes with sharp claws. Its feet are not adapted for swimming. The New Zealand falcon uses its feet to grab prey.


Question: Which of these states is farthest west?

Choices:
- New Mexico
- Kansas
- Maryland
- Alabama

social science

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.

Solution: To find the answer, look at the compass rose. Look at which way the west arrow is pointing. New Mexico is farthest west.


Question: Select the bird below.

Choices:
- flamingo
- cane toad

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

natural science

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.

Solution:
A flamingo is a bird. It has feathers, two wings, and a beak.
A cane toad is an amphibian. It has moist skin and begins its life in water.


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

Choices:
- neither; the samples have the same temperature
- sample A
- sample B

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.

natural science

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.

Solution:
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.


Question: Which property do these two objects have in common?

Choices:
- smooth
- rough

natural science

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.

Solution:
Look at each object.
For each object, decide if it has that property.
A rough object feels scratchy when you touch it. Both objects are rough.
A smooth object is not scratchy or rough. Neither of the objects are smooth.
The property that both objects have in common is rough.


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

Choices:
- The magnitude of the magnetic force is the same in both pairs.
- The magnitude of the magnetic force is greater in Pair 2.
- The magnitude of the magnetic force is greater in Pair 1.

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.

natural science

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.

Solution:
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.


Question: Select the organism in the same species as the brown pelican.

Choices:
- Ardea cocoi
- Ictinia mississippiensis
- Pelecanus occidentalis

This organism is a brown pelican. Its scientific name is Pelecanus occidentalis.

natural science

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.

Solution:
A brown pelican's scientific name is Pelecanus occidentalis.
Ardea cocoi does not have the same scientific name as a brown pelican. So, Pelecanus occidentalis and Ardea cocoi are not in the same species.
Pelecanus occidentalis has the same scientific name as a brown pelican. So, these organisms are in the same species.
Ictinia mississippiensis does not have the same scientific name as a brown pelican. So, Pelecanus occidentalis and Ictinia mississippiensis are not in the same species.


Question: Which fish's mouth is also adapted for tearing through meat?

Choices:
- bull shark
- magnificent rabbitfish

Barracudas often hunt large fish for food. The 's mouth is adapted to tear through meat.
Figure: barracuda.

natural science

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 an animal's mouth is one example of an adaptation. Animals' mouths can be adapted in different ways. For example, a large mouth with sharp teeth might help an animal tear through meat. A long, thin mouth might help an animal catch insects that live in holes. Animals that eat similar food often have similar mouths.

Solution:
Look at the picture of the barracuda.
The barracuda has a large mouth and sharp teeth. Its mouth is adapted for tearing through meat. The baracuda uses its teeth to cut up meat into pieces it can swallow.
Now look at each animal. Figure out which animal has a similar adaptation.
The bull shark has a large mouth and sharp teeth. Its mouth is adapted for tearing through meat.
The magnificent rabbitfish has a small, narrow mouth. Its mouth is not adapted for tearing through meat.


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

Choices:
- The magnitude of the magnetic force is the same in both pairs.
- The magnitude of the magnetic force is greater in Pair 1.
- The magnitude of the magnetic force is greater in Pair 2.

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.

natural science

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.

Solution:
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 1 than in Pair 2. So, the magnitude of the magnetic force is greater in Pair 1 than in Pair 2.


Question: Which of the following could Mitchell's test show?

Choices:
- if the sample fabric would absorb one drop of water in less than one second
- how much athletes would sweat in the fabric
- how long it would take the sample fabric to dry after it absorbed one drop of water

People can use the engineering-design process to develop solutions to problems. One step in the process is testing if a potential solution meets the requirements of the design.
The passage below describes how the engineering-design process was used to test a solution to a problem. Read the passage. Then answer the question below.

Mitchell, a materials engineer, was developing a quick-drying fabric for athletic clothing. The fabric needed to absorb one drop of water in less than one second and dry completely in less than five minutes. Mitchell thought a fabric made from cotton and polyester would both absorb water well and dry quickly. But he needed to decide what percentage of each material to use.
So, he made a sample fabric that was 50% cotton and 50% polyester. Then he put one drop of water on the sample. He timed how long it took the fabric to dry after the water was absorbed.
Figure: fabric that has not absorbed drops of water.

natural science

Evaluate tests of engineering-design solutions

People can use the engineering-design process to develop solutions to problems. One step in the process is testing if a potential solution meets the requirements of the design. How can you determine what a test can show? You need to figure out what was tested and what was measured.
Imagine an engineer needs to design a bridge for a windy location. She wants to make sure the bridge will not move too much in high wind. So, she builds a smaller prototype, or model, of a bridge. Then, she exposes the prototype to high winds and measures how much the bridge moves.
First, identify what was tested. A test can examine one design, or it may compare multiple prototypes to each other. In the test described above, the engineer tested a prototype of a bridge in high wind.
Then, identify what the test measured. One of the criteria for the bridge was that it not move too much in high winds. The test measured how much the prototype bridge moved.
Tests can show how well one or more designs meet the criteria. The test described above can show whether the bridge would move too much in high winds.


Question: Select the organism in the same genus as the Chinese alligator.

Choices:
- Miscanthus sinensis
- Alligator sinensis
- Strix varia

This organism is a Chinese alligator. Its scientific name is Alligator sinensis.

natural science

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.

Solution:
A Chinese alligator's scientific name is Alligator sinensis. The first word of its scientific name is Alligator.
Strix varia is in the genus Strix. The first word of its scientific name is Strix. So, Strix varia and Alligator sinensis are not in the same genus.
Miscanthus sinensis and Alligator sinensis are not in the same genus.
These organisms are not in the same genus, but part of their scientific names is the same. Miscanthus sinensis and Alligator sinensis have the same species name within their genus, sinensis. But the first words of their scientific names are different. Miscanthus sinensis is in the genus Miscanthus, and Alligator sinensis is in the genus Alligator.
This organism and the Chinese alligator are in the same genus and the same species! Both organisms have the same scientific name, Alligator sinensis.


Question: Identify the question that Pablo's experiment can best answer.

Choices:
- Can pennies hold more drops of pure water or water mixed with hand soap?
- Can pennies hold more drops of water mixed with dish soap or water mixed with hand soap?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Pablo used a dropper to put equal-sized drops of pure water, one at a time, onto a penny. The drops stayed together and formed a dome on the penny's surface. Pablo recorded the number of drops he could add before the water spilled over the edge of the penny. Then, he rinsed and dried the penny, and repeated the test using water mixed with hand soap. He repeated these trials on nine additional pennies. Pablo compared the average number of pure water drops to the average number of water drops mixed with hand soap that he could add to a penny before the water spilled over.
Figure: a dome of water on the surface of a penny.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: What is the capital of Arizona?

Choices:
- Helena
- Phoenix
- Tucson
- Honolulu

social science

Solution: Phoenix is the capital of Arizona.


Question: What is the capital of New Hampshire?

Choices:
- Louisville
- Pittsburgh
- Manchester
- Concord

social science

Identify state capitals of the Northeast

Solution: Concord is the capital of New Hampshire.


Question: What is the capital of Oregon?

Choices:
- Billings
- Salem
- Portland
- Salt Lake City

social science

Solution: Salem is the capital of Oregon.


Question: Which country is highlighted?

Choices:
- Cuba
- Haiti
- Trinidad and Tobago
- Grenada

social science

Identify and select countries of the Caribbean

Solution:
This country is Haiti.
Does Haiti have any territorial disputes?
Haiti claims to own Navassa Island, which is a disputed territory. In other words, multiple countries or groups claim that the area rightfully belongs to them.
Navassa Island is also claimed by the United States. The United States claimed the island in 1857 and has controlled it since then. But Haiti considers the island part of its territory and has protested the United States' claim since this time. No one lives on the island. Today, it is a nature preserve.


Question: Select the amphibian below.

Choices:
- robin
- barking tree frog

Amphibians have moist skin and begin their lives in water. An olive toad is an example of an amphibian.

natural science

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.

Solution:
A barking tree frog is an amphibian. It has moist skin and begins its life in water.
A robin is a bird. It has feathers, two wings, and a beak.


Question: What is the name of the colony shown?

Choices:
- Pennsylvania
- Connecticut
- Massachusetts
- Wisconsin

social science

Solution:
The colony is Massachusetts.
The Massachusetts Colony included land that would later become the state of Maine. Maine was never its own colony.


Question: What type of rock is sandstone?

Choices:
- igneous
- metamorphic
- sedimentary

This is a piece of sandstone. Sandstone forms below the ground in places like deserts and beaches. This piece of rock shows dark and light layers.
Sandstone forms from sand grains. Sand grains are tiny pieces of rock that are broken off by water, wind, or ice. Layers of sand can build up in some places. Over time, these layers can get compacted into sandstone.

natural science

Classify rocks as igneous, sedimentary, or metamorphic

Igneous rock is formed when melted rock cools and hardens into solid rock. This type of change can occur at Earth's surface or below it.
Sedimentary rock is formed when layers of sediment are pressed together, or compacted, to make rock. This type of change occurs below Earth's surface.
Metamorphic rock is formed when a rock is changed by very high temperature and pressure. This type of change often occurs deep below Earth's surface. Over time, the old rock becomes a new rock with different properties.

Solution:
Sandstone is a sedimentary rock. Like other sedimentary rocks, it forms from layers of sediment.
Material that is eroded in nature is called sediment. Sand is a type of sediment. Over time, layers of sand can build up in places like deserts and beaches. The top layers press down on the bottom layers, squeezing out water and air. Sandstone forms when the bottom layers of sand are pressed together to form rock.


Question: Is pyrite a mineral?

Choices:
- no
- yes

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

natural science

Properties are used to identify different substances. Minerals have the following properties:
It is a solid.
It is formed in nature.
It is not made by organisms.
It is a pure substance.
It has a fixed crystal structure.
If a substance has all five of these properties, then it is a mineral.
Look closely at the last three properties:
A mineral is 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.
Humans are organisms too. So, substances that humans make by hand or in factories cannot be minerals.
A mineral is a pure substance.
A pure substance is made of only one type of matter. All minerals are pure substances.
A mineral has a fixed crystal structure.
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 or molecules in different pieces of the same type of mineral are always arranged the same way.

Solution: Pyrite has all the properties of a mineral. So, pyrite is a mineral.


Question: Which property do these four objects have in common?

Choices:
- opaque
- salty
- slippery

natural science

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.

Solution:
Look at each object.
For each object, decide if it has that property.
An opaque object does not let light through. All four objects are opaque.
A slippery object is hard to hold onto or stand on. The license plate is not slippery.
Potato chips have a salty taste. The ceramic mug and the banana are not salty.
The property that all four objects have in common is opaque.


Question: What is the capital of Wyoming?

Choices:
- Cheyenne
- Indianapolis
- Carson City
- Santa Fe

social science

Solution: Cheyenne is the capital of Wyoming.


Question: Which solution has a higher concentration of purple particles?

Choices:
- neither; their concentrations are the same
- Solution B
- Solution A

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

natural science

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

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


Question: What can Leo and Caden trade to each get what they want?

Choices:
- Caden can trade his broccoli for Leo's oranges.
- Leo can trade his tomatoes for Caden's carrots.
- Leo can trade his tomatoes for Caden's broccoli.
- Caden can trade his almonds for Leo's tomatoes.

Trade happens when people agree to exchange goods and services. People give up something to get something else. Sometimes people barter, or directly exchange one good or service for another.
Leo and Caden open their lunch boxes in the school cafeteria. Neither Leo nor Caden got everything that they wanted. The table below shows which items they each wanted:

Look at the images of their lunches. Then answer the question below.
Leo's lunch Caden's lunch

social science

Solution:
Look at the table and images.
Leo wants broccoli. Caden wants tomatoes. They can trade tomatoes for broccoli to both get what they want. Trading other things would not help both people get more items they want.


Question: Select the organism in the same genus as the European hedgehog.

Choices:
- Erinaceus europaeus
- Equus zebra
- Caprimulgus europaeus

This organism is a European hedgehog. Its scientific name is Erinaceus europaeus.

natural science

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.

Solution:
A European hedgehog's scientific name is Erinaceus europaeus. The first word of its scientific name is Erinaceus.
Caprimulgus europaeus and Erinaceus europaeus are not in the same genus.
These organisms are not in the same genus, but part of their scientific names is the same. Caprimulgus europaeus and Erinaceus europaeus have the same species name within their genus, europaeus. But the first words of their scientific names are different. Caprimulgus europaeus is in the genus Caprimulgus, and Erinaceus europaeus is in the genus Erinaceus.
Equus zebra is in the genus Equus. The first word of its scientific name is Equus. So, Equus zebra and Erinaceus europaeus are not in the same genus.
This organism and the European hedgehog are in the same genus and the same species! Both organisms have the same scientific name, Erinaceus europaeus.


Question: Identify the question that Peter's experiment can best answer.

Choices:
- Do steel nails take fewer days to rust in water compared to vinegar?
- Do steel nails rust in fewer days when submerged in a large volume of liquid compared to a small volume?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Peter put one two-inch steel nail into each of six test tubes. He added water to three of the test tubes and vinegar to the other three. In each test tube, he completely covered the nail with the same volume of liquid. Peter checked the nails for rust at the same time every day. He recorded how many days it took each nail to become completely covered in rust. Then, he compared the number of days it took nails to rust in water to the number of days it took nails to rust in vinegar.
Figure: a new steel nail on a pile of rusty nails.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: Which is the main persuasive appeal used in this ad?

Choices:
- logos (reason)
- ethos (character)
- pathos (emotion)

language science

Identify appeals to ethos, pathos, and logos in advertisements

The purpose of an advertisement is to persuade people to do something. To accomplish this purpose, advertisements use three types of persuasive strategies, or appeals:
Appeals to ethos, or character, show that the writer or speaker is trustworthy or is an authority on a subject. An ad that appeals to ethos might do one of the following:
say that a brand has been trusted for many years
note that a brand is recommended by a respected organization or celebrity
include a quote from a "real person" who shares the audience's values
Appeals to logos, or reason, use logic and specific evidence. An ad that appeals to logos might do one of the following:
use graphs or charts to display information
mention the results of scientific studies
explain the science behind a product or service
Appeals to pathos, or emotion, use feelings rather than facts to persuade the audience. An ad that appeals to pathos might do one of the following:
trigger a fear, such as the fear of embarrassment
appeal to a desire, such as the desire to appear attractive
link the product to a positive feeling, such as adventure, love, or luxury

Solution: The ad appeals to logos, or reason. It mentions the results of laboratory tests.


Question: What is the capital of South Dakota?

Choices:
- Arlington
- Madison
- Springfield
- Pierre

social science

Solution: Pierre is the capital of South Dakota.


Question: Based on the Venn diagram, what do Natty Bumppo and Daniel Boone have in common?

Choices:
- Both fought in the French and Indian War.
- Both were created by writer James Fenimore Cooper.

language science

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.

Solution:
In a Venn diagram, each circle shows things that are true for a particular topic. The middle, where the two circles overlap, shows things that are true for both topics. This Venn diagram compares Natty Bumppo and Daniel Boone.
Fought in the French and Indian War appears in both the Natty Bumppo circle and the Daniel Boone circle. This tells you that Natty Bumppo and Daniel Boone both fought in the French and Indian War.


Question:
Is the following statement about our solar system true or false?
50% of the planets are made mainly of gas.

Choices:
- true
- false

Use the data to answer the question below.

natural science

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.

Solution: The table tells you that two out of the eight planets are made mainly of gas. So, one-fourth, or 25%, of the planets are made mainly of gas.


Question: Select the organism in the same species as the comet moth.

Choices:
- Sphodromantis viridis
- Argema mittrei
- Acanthaster planci

This organism is a comet moth. Its scientific name is Argema mittrei.

natural science

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.

Solution:
A comet moth's scientific name is Argema mittrei.
Argema mittrei has the same scientific name as a comet moth. So, these organisms are in the same species.
Sphodromantis viridis does not have the same scientific name as a comet moth. So, Argema mittrei and Sphodromantis viridis are not in the same species.
Acanthaster planci does not have the same scientific name as a comet moth. So, Argema mittrei and Acanthaster planci are not in the same species.


Question:
Complete the text to describe the diagram.
Solute particles moved in both directions across the permeable membrane. But more solute particles moved across the membrane (). When there was an equal concentration on both sides, the particles reached equilibrium.

Choices:
- to the left than to the right
- to the right than to the left

The diagram below shows a solution with one solute. Each solute particle is represented by a pink ball. The solution fills a closed container that is divided in half by a membrane. The membrane, represented by a dotted line, is permeable to the solute particles.
The diagram shows how the solution can change over time during the process of diffusion.

natural science

In a solution, solute particles move and spread throughout the solvent. The diagram below shows how a solution can change over time. Solute particles move from the area where they are at a higher concentration to the area where they are at a lower concentration. This movement happens through the process of diffusion.
As a result of diffusion, the concentration of solute particles becomes equal throughout the solution. When this happens, the solute particles reach equilibrium. At equilibrium, the solute particles do not stop moving. But their concentration throughout the solution stays the same.
Membranes, or thin boundaries, can divide solutions into parts. A membrane is permeable to a solute when particles of the solute can pass through gaps in the membrane. In this case, solute particles can move freely across the membrane from one side to the other.
So, for the solute particles to reach equilibrium, more particles will move across a permeable membrane from the side with a higher concentration of solute particles to the side with a lower concentration. At equilibrium, the concentration on both sides of the membrane is equal.

Solution:
Look at the diagram again. It shows you how the solution changed during the process of diffusion.
Before the solute particles reached equilibrium, there were 2 solute particles on the left side of the membrane and 6 solute particles on the right side of the membrane.
When the solute particles reached equilibrium, there were 4 solute particles on each side of the membrane. There were 2 more solute particles on the left side of the membrane than before.
So, for the solute particles to reach equilibrium, more solute particles must have moved across the membrane to the left than to the right.


Question: Based on the bubble map, which statement is true?

Choices:
- The Gulf of Mexico contains salt water.
- Lake Michigan contains salt water.

language science

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.

Solution:
A bubble map uses lines to connect things that are related. This bubble map shows information about different bodies of water.
Gulf of Mexico is directly connected to salt water. This tells you that the Gulf of Mexico contains salt water.


Question: Which of these states is farthest east?

Choices:
- California
- Idaho
- New Mexico
- Nebraska

social science

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.

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


Question: Which statement describes the Steigerwald Forest ecosystem?

Choices:
- It has soil that is poor in nutrients.
- It has soil that is rich in nutrients.

Figure: Steigerwald Forest.
The Steigerwald Forest is a temperate deciduous forest ecosystem in Bavaria, a state in southern Germany. This forest has many oak and beech trees.

natural science

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

Solution: 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, the following statements describe the Steigerwald Forest ecosystem: warm, wet summers and cold, wet winters, soil that is rich in nutrients, and only a few types of trees. It has soil that is rich in nutrients. It has warm, wet summers and cold, wet winters. The following statement does not describe the Steigerwald Forest: warm, wet summers and cold, wet winters, soil that is rich in nutrients, and only a few types of trees. It has soil that is poor in nutrients.


Question: What is the capital of Alabama?

Choices:
- Tallahassee
- Frankfort
- Montgomery
- Birmingham

social science

Identify state capitals of the Southeast

Solution: Montgomery is the capital of Alabama.


Question: Which of these states is farthest south?

Choices:
- Wisconsin
- Pennsylvania
- Indiana
- Oklahoma

social science

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.

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


Question: Which better describes the De Biesbosch National Park ecosystem?

Choices:
- It has soil that is rich in nutrients. It also has other water ecosystems nearby.
- It has soil that is poor in nutrients. It also has other water ecosystems nearby.

Figure: De Biesbosch National Park.
De Biesbosch National Park is a wetland ecosystem in the Netherlands.

natural science

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

Solution: A wetland is a type of ecosystem. Wetlands have the following features: land that is covered with water during most of the year, soil that is rich in nutrients, and other water ecosystems nearby. So, De Biesbosch National Park has soil that is rich in nutrients. It also has other water ecosystems nearby.


Question: Based on the time line, what does Romeo do after he fights with Tybalt?

Choices:
- He makes a plan with Juliet to run away.
- He meets Juliet at the ball.

language science

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.

Solution:
A time line shows the order of events by placing them along a line. This time line shows events from Romeo and Juliet by William Shakespeare.
Look at how the events are ordered on the time line. Events that happen earlier are shown to the left. Events that happen later are shown to the right. Romeo and Juliet plan to run away is shown to the right of Tybalt fights with Romeo. So, after Romeo fights with Tybalt, Romeo and Juliet plan to run away.


Question: What is the capital of Wyoming?

Choices:
- Seattle
- Cheyenne
- Tucson
- Trenton

social science

Solution: Cheyenne is the capital of Wyoming.


Question: Earth's organisms rely on the atmosphere for which of the following?

Choices:
- stable temperatures
- sunlight

Read the text. Then answer the question.
Earth is surrounded by a layer of gases called the atmosphere. The gases that make up the atmosphere sustain life on Earth. Living organisms take in and release some of these gases. Gases in the atmosphere also help insulate Earth from extreme temperatures and block some harmful forms of sunlight.

natural science

Solution:
Read the text carefully. The underlined text below shows information about each answer choice.
Earth is surrounded by a layer of gases called the atmosphere. The gases that make up the atmosphere sustain life on Earth. Living organisms take in and release some of these gases. Gases in the atmosphere also help insulate Earth from extreme temperatures and block some harmful forms of sunlight.
Earth's atmosphere contains many different gases, including oxygen and carbon dioxide. These gases are both taken in and released by living organisms. Animals breathe in oxygen and breathe out carbon dioxide. Plants use carbon dioxide and release oxygen during photosynthesis.
Some of the gases that make up the atmosphere also insulate Earth, helping to maintain its stable temperatures.
While many gases interact with sunlight, Earth's atmosphere does not provide sunlight.


Question: Which solution has a higher concentration of blue particles?

Choices:
- neither; their concentrations are the same
- Solution A
- Solution B

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

natural science

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

Solution:
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.


Question:
Is the following statement about our solar system true or false?
75% of the planets are made mainly of rock.

Choices:
- false
- true

Use the data to answer the question below.

natural science

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.

Solution: The table tells you that four out of the eight planets are made mainly of rock. So, one-half, or 50%, of the planets are made mainly of rock.


Question: Which material is this bucket made of?

Choices:
- metal
- porcelain

natural science

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.

Solution:
Look at the picture of the bucket.
The bucket is made of two different materials. The body is made of plastic, and the handle is made of metal.
Plastic is a great material for buckets because plastic is waterproof.


Question: Which term matches the picture?

Choices:
- Cenozoic era
- Mesozoic era

Read the text.
Scientists divide the history of Earth into eras. Different types of animal life help distinguish these eras. We live in the Cenozoic era, which began roughly sixty-six million years ago. The Cenozoic era is known as the Age of Mammals because mammals, like humans, are the largest land animals. During the previous era, called the Mesozoic era, big reptiles, like dinosaurs, were the dominant animal species—it's nicknamed the Age of Reptiles. Some scientists believe that, at the end of the Mesozoic era, a large object from space collided with Earth, helping cause the mass extinction of the dinosaurs and ushering in the Age of Mammals.

language science

Determine the meaning of domain-specific words with pictures

Solution: The Mesozoic era is also known as the Age of Reptiles. During the Mesozoic era, reptiles like dinosaurs were the dominant animal species.


Question: What can a fern spore grow into?

Choices:
- a mature fern
- a heart-shaped plant

This diagram shows the life cycle of a fern.

natural science

Fern plants reproduce using both asexual reproduction and sexual reproduction.
Mature ferns have flat leaves called fronds. Ferns have structures that look like small dots on the underside of their fronds. These structures are called spore cases. The mature ferns use asexual reproduction to make spores. When the spore cases open, the spores are released.
When a spore lands on the ground and germinates, it grows into a small heart-shaped plant. The heart-shaped plant begins the fern's sexual reproduction stage by making eggs and sperm. Ferns live in damp environments, and sperm can swim though small water drops. Self-fertilization happens when a sperm swims to an egg on the same heart-shaped plant. Cross-fertilization happens when the sperm swims to an egg on a nearby plant.
Fertilization happens when a sperm and an egg fuse. The fertilized egg germinates and grows into a mature fern.
The mature fern can make spores and begin the fern life cycle again.

Solution:
After they are released, spores can land on the ground and germinate. When a spore germinates, it grows into a heart-shaped plant.
Mature fern plants grow from fertilized eggs.


Question: Which country is highlighted?

Choices:
- Tuvalu
- the Marshall Islands
- Kiribati
- Nauru

social science

Identify and select countries of Oceania

Solution: This country is Kiribati.