Question: Which is this organism's common name?

Choices:
- Gymnothorax funebris
- green moray eel

This organism is Gymnothorax funebris. It is also called a green moray eel.

natural science

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

Solution:
Gymnothorax funebris is written in italics. The first word is capitalized, and the second word is not. So, it is the scientific name.
Gymnothorax funebris is the organism's scientific name. So, you know that green moray eel is the common name.


Question: Which rhetorical appeal is primarily used in this ad?

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

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 the writer or speaker as trustworthy, authoritative, or sharing important values with the audience. An ad that appeals to ethos might do one of the following:
say that a brand has been trusted for many years
include an endorsement from a respected organization, such as the American Dental Association
feature a testimonial from a "real person" who shares the audience's values
use an admired celebrity or athlete as a spokesperson
Appeals to logos, or reason, use logic and verifiable evidence. An ad that appeals to logos might do one of the following:
use graphs or charts to display information
cite results of clinical trials or independently conducted studies
explain the science behind a product or service
emphasize that the product is a financially wise choice
anticipate and refute potential counterclaims
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, by emphasizing the practical benefits users can expect from the car.


Question: Which of these states is farthest west?

Choices:
- Maine
- Rhode Island
- Wisconsin
- North Dakota

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. North Dakota is farthest west.


Question:
Complete the statement.
Gold is ().

Choices:
- an elementary substance
- a compound

The model below represents gold. Gold is a precious metal that is often used to make jewelry.

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 fluorine is F, and the atomic symbol for the chemical element beryllium is Be.
Scientists use different types of models to represent substances whose atoms are bonded in different ways. One type of model is a space-filling model. The space-filling model below represents the elementary substance zirconium.
In a space-filling model, the balls represent atoms that are bonded together. The color of a ball represents a specific chemical element. The atomic symbol for that chemical element is shown in the legend.

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


Question: What can happen to a sperm and an egg?

Choices:
- They can turn into spores.
- They can fuse and form fertilized eggs.

This diagram shows the life cycle of a moss.

natural science

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

Solution:
A sperm and an egg can fuse to form a fertilized egg. The fertilized egg then grows into a thin brown stalk on top of the female part.
The new stalk may make spores, but the sperm and the egg do not turn into spores.


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

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

Solution:
Distance affects the strength of the magnetic force. But the distance between the magnets in Pair 1 and in Pair 2 is the same.
So, the strength of the magnetic force is the same in both pairs.


Question: Which country is highlighted?

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

social science

Identify and select countries of Oceania

Solution: This country is Nauru.


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

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

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


Question: Select the bird below.

Choices:
- western toad
- barn owl

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 barn owl is a bird. It has feathers, two wings, and a beak.
A western toad is an amphibian. It has moist skin and begins its life in water.


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: What is the capital of Hawaii?

Choices:
- Burlington
- Indianapolis
- Honolulu
- Little Rock

social science

Solution: Honolulu is the capital of Hawaii.


Question: What is the capital of Arizona?

Choices:
- Tallahassee
- Cheyenne
- Honolulu
- Phoenix

social science

Solution: Phoenix is the capital of Arizona.


Question: Will these magnets attract or repel each other?

Choices:
- attract
- repel

natural science

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

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


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

Choices:
- sample B
- sample A
- 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:
Each particle in sample B has more mass than each particle in sample A. The particles in sample B also have a higher average speed than the particles 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: What is the capital of Ohio?

Choices:
- Montgomery
- Cleveland
- Cincinnati
- Columbus

social science

Solution: Columbus is the capital of Ohio.


Question: What is the capital of Florida?

Choices:
- Tallahassee
- Orlando
- Tampa
- Oklahoma City

social science

Identify state capitals of the Southeast

Solution: Tallahassee is the capital of Florida.


Question:
Complete the statement.
Silver is ().

Choices:
- an elementary substance
- a compound

The model below represents silver. Silver is a precious metal that is used to make many items, such as jewelry and coins.

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 fluorine is F, and the atomic symbol for the chemical element beryllium is Be.
Scientists use different types of models to represent substances whose atoms are bonded in different ways. One type of model is a space-filling model. The space-filling model below represents the elementary substance zirconium.
In a space-filling model, the balls represent atoms that are bonded together. The color of a ball represents a specific chemical element. The atomic symbol for that chemical element is shown in the legend.

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


Question: After the Akkadian Empire ended, many cities and empires tried to control Mesopotamia. Around the 1790s BCE, which empire started controlling Mesopotamia?

Choices:
- the Elamite Empire
- the Neo-Sumerian Empire
- the Babylonian Empire
- the Akkadian Empire

Look at the table. Then answer the question below.

social science

Solution:
Look at the table.
The abbreviation "ca." stands for the Latin word, circa. Circa means "about." It indicates when a date is estimated. So, around 1792 BCE, the Babylonian Empire started controlling Mesopotamia.
The Babylonian (ba-bih-LOH-nee-in) Empire came after the Akkadian and Neo-Sumerian empires. The capital of the Babylonian Empire was the city of Babylon (BA-bih-lahn).


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

Choices:
- African crowned eagle
- California gull

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

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 Atlantic puffin.
The Atlantic puffin has webbed feet. Its feet are adapted for swimming. As it swims, the Atlantic puffin uses its webbed feet to push itself through water.
Now look at each animal. Figure out which animal has a similar adaptation.
The California gull has small claws and webbed feet. Its feet are adapted for swimming.
The African crowned eagle has long toes with sharp claws. Its feet are not adapted for swimming. The African crowned eagle uses its feet to grab prey.


Question: Which continent is highlighted?

Choices:
- Asia
- Antarctica
- Australia

social science

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

Solution: This continent is Asia.


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, 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:
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 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: Will these magnets attract or repel each other?

Choices:
- attract
- repel

Two magnets are placed as shown.

Hint: Magnets that attract pull together. Magnets that repel push apart.

natural science

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

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


Question: Select the bird below.

Choices:
- sea otter
- white stork

Birds have feathers, two wings, and a beak. A penguin 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 sea otter is a mammal. It has fur and feeds its young milk.
Sea otters have very thick fur. Their fur keeps them warm in cold water.
A white stork is a bird. It has feathers, two wings, and a beak.
Storks wade in shallow water to look for food. Storks eat fish, insects, worms, and other small animals.


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 2.
- The strength of the magnetic force is the same in both pairs.
- The magnetic force is stronger 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 stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.


Question: Will these magnets attract or repel each other?

Choices:
- attract
- repel

Two magnets are placed as shown.

Hint: Magnets that attract pull together. Magnets that repel push apart.

natural science

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

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


Question: What grows in a fertilized cone?

Choices:
- pollen
- seeds

This diagram shows the life cycle of a pine tree.

natural science

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

Solution:
Fertilized eggs grow into seeds inside a fertilized cone.
Pollen grows inside male cones, not fertilized cones.


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

Choices:
- sticky
- stretchy
- 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.
A stretchy object gets longer when you pull on it. The chocolate milkshake is not stretchy.
A sticky object can attach or stick to other things. All four objects are sticky.
A slippery object is hard to hold onto or stand on. The tape is not slippery.
The property that all four objects have in common is sticky.


Question: What can Mandy and Troy trade to each get what they want?

Choices:
- Troy can trade his broccoli for Mandy's oranges.
- Mandy can trade her tomatoes for Troy's carrots.
- Troy can trade his almonds for Mandy's tomatoes.
- Mandy can trade her tomatoes for Troy'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.
Mandy and Troy open their lunch boxes in the school cafeteria. Neither Mandy nor Troy 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.
Mandy's lunch Troy's lunch

social science

Solution:
Look at the table and images.
Mandy wants broccoli. Troy 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: In this food chain, the California sea slug is a consumer. Why?

Choices:
- It eats another living thing.
- It makes its own food.

This diagram shows a food chain from Monterey Bay, an ocean ecosystem on the coast of California.

natural science

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

Solution: In this food chain, the California sea slug is a consumer because it eats another living thing. The California sea slug in this food chain eats the kelp.


Question: Which three months have over 200millimeters of precipitation in Singapore?

Choices:
- May, June, and July
- August, September, and October
- November, December, and January

Use the graph to answer the question below.

natural science

Scientists record climate data from places around the world. Precipitation, or rain and snow, is one type of climate data. Scientists collect data over many years. They can use this data to calculate the average precipitation for each month. The average precipitation can be used to describe the climate of a location.
A bar graph can be used to show the average amount of precipitation each month. Months with taller bars have more precipitation on average.

Solution:
To describe the average precipitation trends in Singapore, look at the graph.
Choice "Jan" is incorrect.
Choice "May" is incorrect.
Choice "Jun" is incorrect.
Choice "Jul" is incorrect.
Choice "Aug" is incorrect.
Choice "Sep" is incorrect.
Choice "Oct" is incorrect.
Choice "Nov" is incorrect.
Choice "Dec" is incorrect.
November, December, and January each have over 200 millimeters of precipitation.


Question: In this experiment, which were part of a control group?

Choices:
- the uncovered side mirrors
- the covered side mirrors

The passage below describes an experiment.

On winter mornings, Lucia had to scrape the ice off of the windshield and side mirrors of her car. Her friend told her that she should cover her side mirrors with plastic bags overnight to stop ice from forming.
One winter night, Lucia secured a plastic bag over one of the side mirrors on her car. She left the other side mirror uncovered. In the morning, she checked the percentage of each mirror that was covered by ice. Lucia repeated this test every night for one week, alternating which mirror she covered each night.
Figure: a side mirror covered in ice.

natural science

Identify control and experimental groups

Experiments have variables, or parts that change. You can design an experiment to investigate whether changing a variable between different groups has a specific outcome.
For example, imagine you want to find out whether adding fertilizer to soil affects the height of pea plants. You could investigate this question with the following experiment:
You grow one group of pea plants in soil with fertilizer and measure the height of the plants. This group shows you what happens when fertilizer is added to soil. Since fertilizer is the variable whose effect you are investigating, this group is an experimental group.
You grow another group of pea plants in soil without fertilizer and measure the height of the plants. Since this group shows you what happens when fertilizer is not added to the soil, it is a control group.
By comparing the results from the experimental group to the results from the control group, you can conclude whether adding fertilizer to the soil affects pea plant height.

Solution: In this experiment, Lucia investigated whether covering side mirrors with plastic bags affects how much ice forms on the mirrors. There were no bags on the uncovered side mirrors. So, they were part of a control group.


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.

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 smaller when there is a greater distance between the magnets.

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


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

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.

Solution:
Both magnet sizes and distance affect the magnitude of the magnetic force. The sizes of the magnets in Pair 1 are the same as in Pair 2. The distance between the magnets is also the same.
So, the magnitude of the magnetic force is the same in both pairs.


Question: Which continent is highlighted?

Choices:
- Africa
- Asia
- Australia
- North America

social science

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

Solution: This continent is North America.


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

Choices:
- wood
- palm leaf

This diagram shows fossils in an undisturbed sedimentary rock sequence.

natural science

Compare ages of fossils in a rock sequence

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

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


Question: Is a stuffed hippo a solid, a liquid, or a gas?

Choices:
- a gas
- a liquid
- a solid

natural science

Classify matter as solid, liquid, or gas

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

Solution:
A stuffed hippo is a solid. A solid has a size and shape of its own.
When you hold a stuffed hippo in your hands, the stuffed hippo still has a size and shape of its own.


Question: Which better describes the Great Victoria Desert ecosystem?

Choices:
- It has a small amount of rain. It also has soil that is frozen year-round.
- It has a small amount of rain. It also has dry, thin soil.

Figure: Great Victoria Desert.
The Great Victoria Desert is a hot desert ecosystem located in Western Australia and South Australia.

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 hot desert is a type of ecosystem. Hot deserts have the following features: a small amount of rain, dry, thin soil, and many different types of organisms. So, the Great Victoria Desert has a small amount of rain. It also has dry, thin soil.


Question: What is the name of the colony shown?

Choices:
- Delaware
- Kentucky
- New York
- Vermont

social science

Solution:
The colony is New York.
During the colonial era, New Hampshire and New York both claimed the territory that would later become the state of Vermont. Vermont was never its own colony.


Question: Is plagioclase a mineral or a rock?

Choices:
- rock
- mineral

Plagioclase has the following properties:
white streak
fixed crystal structure
pure substance
naturally occurring
not made by organisms
solid

natural science

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

Solution: Plagioclase has all the properties of a mineral. So, plagioclase is a mineral.


Question: Which property matches this object?

Choices:
- soft
- fragile

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 fragile object will break into pieces if you drop it. The glass is fragile.
A soft object changes shape when pressed or squeezed. The glass is not soft.


Question: Which property matches this object?

Choices:
- sour
- bumpy

natural science

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

Solution:
Look at the object.
Think about each property.
A lemon has a sour taste. The popcorn is not sour.
A bumpy object is covered in lumps and bumps. The popcorn is bumpy.


Question: What is the capital of Hawaii?

Choices:
- Honolulu
- Buffalo
- Annapolis
- Saint Louis

social science

Solution: Honolulu is the capital of Hawaii.


Question: Which state is highlighted?

Choices:
- Idaho
- Wyoming
- Colorado
- Nevada

social science

Solution: This state is Wyoming.


Question: What can Pedro and Oliver trade to each get what they want?

Choices:
- Oliver can trade his almonds for Pedro's tomatoes.
- Oliver can trade his broccoli for Pedro's oranges.
- Pedro can trade his tomatoes for Oliver's carrots.
- Pedro can trade his tomatoes for Oliver'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.
Pedro and Oliver open their lunch boxes in the school cafeteria. Neither Pedro nor Oliver 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.
Pedro's lunch Oliver's lunch

social science

Solution:
Look at the table and images.
Pedro wants broccoli. Oliver 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 is also adapted to be camouflaged in the snow?

Choices:
- naked mole rat
- ptarmigan

es live in the cold Arctic tundra. The  is adapted to be camouflaged in the snow.
Figure: Arctic fox.

natural science

Animal adaptations: skins and body coverings

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors.
The color, texture, and covering of an animal's skin are examples of adaptations. Animals' skins can be adapted in different ways. For example, skin with thick fur might help an animal stay warm. Skin with sharp spines might help an animal defend itself against predators.

Solution:
Look at the picture of the Arctic fox.
During the winter, the Arctic fox has white fur covering its body. It is adapted to be camouflaged in the snow. The word camouflage means to blend in.
Now look at each animal. Figure out which animal has a similar adaptation.
During the winter, the ptarmigan has white feathers covering its body. It is adapted to be camouflaged in the snow.
The naked mole rat has thin pink skin. It is not adapted to be camouflaged in the snow.


Question: What is the capital of Idaho?

Choices:
- Olympia
- Saint Louis
- Cincinnati
- Boise

social science

Solution: Boise is the capital of Idaho.


Question: What is the capital of Missouri?

Choices:
- Juneau
- Chicago
- Jefferson City
- Madison

social science

Solution: Jefferson City is the capital of Missouri.


Question: What is the capital of New Mexico?

Choices:
- Helena
- Colorado Springs
- Santa Fe
- Albuquerque

social science

Solution: Santa Fe is the capital of New Mexico.


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

Choices:
- tokay gecko
- groundhog

s are found in many parts of Europe. They dig and live in burrows. These moles eat earthworms and nuts, which they find in the soil. The feet of the  are adapted for digging.
Figure: European mole.

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 European mole.
The European mole has long, straight claws. Its feet are adapted for digging. The European mole uses its claws to break up soil and move it out of the way.
Now look at each animal. Figure out which animal has a similar adaptation.
The groundhog has long, straight claws. Its feet are adapted for digging.
The tokay gecko has wide, sticky toes. Its feet are not adapted for digging. The tokay gecko uses its feet to climb trees and walk on leaves.


Question: Which animal's skin is better adapted as a warning sign to ward off predators?

Choices:
- gray tree frog
- Spanish shawl nudibranch

Strawberry poison frogs have poisonous glands in their brightly colored skin. The bright colors serve as a warning sign that the animal is poisonous. The 's skin is adapted to ward off predators.
Figure: strawberry poison frog.

natural science

Animal adaptations: skins and body coverings

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors.
The color, texture, and covering of an animal's skin are examples of adaptations. Animals' skins can be adapted in different ways. For example, skin with thick fur might help an animal stay warm. Skin with sharp spines might help an animal defend itself against predators.

Solution:
Look at the picture of the strawberry poison frog.
The strawberry poison frog has poisonous glands in its brightly colored skin. Its skin is adapted to ward off predators. The bright colors serve as a warning sign that the strawberry poison frog is poisonous.
Now look at each animal. Figure out which animal has a similar adaptation.
The Spanish shawl nudibranch has stinging cells in its brightly colored skin. Its skin is adapted to ward off predators.
The gray tree frog has gray-brown skin. Its skin is not adapted to be a warning sign that wards off predators.


Question: What is the capital of Pennsylvania?

Choices:
- Trenton
- Philadelphia
- Harrisburg
- Albany

social science

Identify state capitals of the Northeast

Solution: Harrisburg is the capital of Pennsylvania.


Question: Which continent is highlighted?

Choices:
- Africa
- Asia
- Antarctica
- South America

social science

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

Solution: This continent is South America.


Question: Which of the following was a dependent variable in this experiment?

Choices:
- the distance the footballs traveled
- the air pressure in the footballs

The passage below describes an experiment. Read the passage and think about the variables that are described.

Kamal noticed that some of the footballs his team used during practice were not fully inflated. He wondered whether fully inflated footballs would travel farther than footballs with a lower air pressure.
To find out, Kamal collected 20 standard footballs. He fully inflated ten of them to an air pressure of 13 pounds per square inch. He inflated the remaining ten to an air pressure of 10 pounds per square inch. Kamal used  to launch a ball across a football field. He measured the distance the football traveled and then launched the next ball. Kamal repeated this with all 20 balls.
Hint: An independent variable is a variable whose effect you are investigating. A dependent variable is a variable that you measure.
Figure: a football launcher.

natural science

Identify independent and dependent variables

Experiments have variables, or parts that change. You can design an experiment to find out how one variable affects another variable. For example, imagine that you want to find out if fertilizer affects the number of tomatoes a tomato plant grows. To answer this question, you decide to set up two equal groups of tomato plants. Then, you add fertilizer to the soil of the plants in one group but not in the other group. Later, you measure the effect of the fertilizer by counting the number of tomatoes on each plant.
In this experiment, the amount of fertilizer added to the soil and the number of tomatoes were both variables.
The amount of fertilizer added to the soil was an independent variable because it was the variable whose effect you were investigating. This type of variable is called independent because its value does not depend on what happens after the experiment begins. Instead, you decided to give fertilizer to some plants and not to others.
The number of tomatoes was a dependent variable because it was the variable you were measuring. This type of variable is called dependent because its value can depend on what happens in the experiment.


Question: Which better describes the Cerrado ecosystem?

Choices:
- It has warm summers and warm winters. It also has year-round rain.
- It has a rainy season and a dry season. It also has soil that is poor in nutrients.

Figure: Cerrado.
The Cerrado is a savanna grassland ecosystem in Brazil.

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 savanna grassland is a type of ecosystem. Savanna grasslands have the following features: warm summers and warm winters, a rainy season and a dry season, and soil that is poor in nutrients. So, the Cerrado has a rainy season and a dry season. It also has soil that is poor in nutrients.


Question: Select the chemical formula for this molecule.

Choices:
- H3S2
- He2S2
- H2S
- H2SN

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:
H is the symbol for hydrogen. S is the symbol for sulfur. This ball-and-stick model shows a molecule with two hydrogen atoms and one sulfur atom.
The chemical formula will contain the symbols H and S. There are two hydrogen atoms, so H will have a subscript of 2. There is one sulfur atom, so S will not have a subscript.
The correct formula is H2 S.
The diagram below shows how each part of the chemical formula matches with each part of the model above.


Question: What is the capital of Missouri?

Choices:
- Madison
- Albuquerque
- Jefferson City
- Kansas City

social science


Question: What is the direction of this pull?

Choices:
- toward her hand
- away from her hand

A student opens her desk drawer. She uses a force to pull out the drawer.

natural science

A force is a push or a pull that one object applies to another. Every force has a direction.
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 pulls open her desk drawer. The direction of the pull is toward her hand.


Question: What is the capital of Michigan?

Choices:
- Lansing
- Providence
- San Francisco
- Wilmington

social science

Solution: Lansing is the capital of Michigan.


Question: Select the organism in the same species as the peregrine falcon.

Choices:
- Falco peregrinus
- Strix uralensis
- Ardea cinerea

This organism is a peregrine falcon. Its scientific name is Falco peregrinus.

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 peregrine falcon's scientific name is Falco peregrinus.
Ardea cinerea does not have the same scientific name as a peregrine falcon. So, Falco peregrinus and Ardea cinerea are not in the same species.
Strix uralensis does not have the same scientific name as a peregrine falcon. So, Falco peregrinus and Strix uralensis are not in the same species.
Falco peregrinus has the same scientific name as a peregrine falcon. So, these organisms are in the same species.


Question:
Complete the statement.
Magnesium is ().

Choices:
- an elementary substance
- a compound

The model below represents magnesium. Magnesium burns easily in air, so it is often used as a fire starter.

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 fluorine is F, and the atomic symbol for the chemical element beryllium is Be.
Scientists use different types of models to represent substances whose atoms are bonded in different ways. One type of model is a space-filling model. The space-filling model below represents the elementary substance zirconium.
In a space-filling model, the balls represent atoms that are bonded together. The color of a ball represents a specific chemical element. The atomic symbol for that chemical element is shown in the legend.

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


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, but some of them are different sizes and shapes.

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


Question: Which state is highlighted?

Choices:
- Mississippi
- North Carolina
- Arkansas
- Louisiana

social science

Solution: This state is Arkansas.


Question: Select the organism in the same species as the moon jellyfish.

Choices:
- Aequorea victoria
- Aurelia aurita
- Cyanea capillata

This organism is a moon jellyfish. Its scientific name is Aurelia aurita.

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 moon jellyfish's scientific name is Aurelia aurita.
Aurelia aurita has the same scientific name as a moon jellyfish. So, these organisms are in the same species.
Cyanea capillata does not have the same scientific name as a moon jellyfish. So, Aurelia aurita and Cyanea capillata are not in the same species.
Aequorea victoria does not have the same scientific name as a moon jellyfish. So, Aurelia aurita and Aequorea victoria are not in the same species.


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

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

The diagram below is a model of two solutions. Each green 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 green particles represent the solute. To figure out which solution has a higher concentration of green particles, look at both the number of green particles and the volume of the solvent in each container.
Use the concentration formula to find the number of green particles per milliliter.
Solution B has more green particles per milliliter. So, Solution B has a higher concentration of green particles.


Question: Which animal's mouth is also adapted for gnawing?

Choices:
- Damara mole rat
- aardvark

Marmots eat plant matter, such as leaves, stems, and seeds. They eat by biting off small pieces at a time, or gnawing. The 's mouth is adapted for gnawing.
Figure: marmot.

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 marmot.
The marmot has large front teeth. Its mouth is adapted for gnawing. The large front teeth can help the marmot break off pieces of food that it can swallow.
Now look at each animal. Figure out which animal has a similar adaptation.
The Damara mole rat has large front teeth. Its mouth is adapted for gnawing.
The aardvark has a long tube-shaped mouth and a few, small teeth. Its mouth is not adapted for gnawing. The aardvark uses its mouth to get insects out of holes and burrows.


Question: Which better describes the Kermadec Arc ecosystem?

Choices:
- It has bright sunlight. It also has organisms that crawl or stick to the ground.
- It has water at the bottom of the ocean. It also has no sunlight.

Figure: Kermadec Arc.
The Kermadec Arc is a deep sea ecosystem in the southern Pacific Ocean.

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: The deep sea is a type of ecosystem. Deep sea ecosystems have the following features: water at the bottom of the ocean, no sunlight, and organisms that crawl or stick to the ground. So, the Kermadec Arc has water at the bottom of the ocean. It also has no sunlight.


Question: Which of the following could Martina and Kiera's test show?

Choices:
- if a new batch of concrete was firm enough to use
- if the concrete from each batch took the same amount of time to dry

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.

Martina and Kiera were making batches of concrete for a construction project. To make the concrete, they mixed together dry cement powder, gravel, and water. Then, they checked if each batch was firm enough using a test called a slump test.
They poured some of the fresh concrete into an upside-down metal cone. They left the concrete in the metal cone for 30 seconds. Then, they lifted the cone to see if the concrete stayed in a cone shape or if it collapsed. If the concrete in a batch collapsed, they would know the batch should not be used.
Figure: preparing a concrete slump test.

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: Which solution has a higher concentration of blue particles?

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

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: Select the organism in the same genus as the mouflon.

Choices:
- Hystrix cristata
- Alouatta palliata
- Ovis aries

This organism is a mouflon. Its scientific name is Ovis orientalis.

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 mouflon's scientific name is Ovis orientalis. The first word of its scientific name is Ovis.
Alouatta palliata is in the genus Alouatta. The first word of its scientific name is Alouatta. So, Alouatta palliata and Ovis orientalis are not in the same genus.
Ovis aries is in the genus Ovis. The first word of its scientific name is Ovis. So, Ovis aries and Ovis orientalis are in the same genus.
Hystrix cristata is in the genus Hystrix. The first word of its scientific name is Hystrix. So, Hystrix cristata and Ovis orientalis are not in the same genus.


Question: Will these magnets attract or repel each other?

Choices:
- repel
- attract

Two magnets are placed as shown.

Hint: Magnets that attract pull together. Magnets that repel push apart.

natural science

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

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


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

Choices:
- The strength of the magnetic force is the same in both pairs.
- The magnetic force is weaker in Pair 2.
- The magnetic force is weaker 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 stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.

Solution:
Distance affects the strength of the magnetic force. But the distance between the magnets in Pair 1 and in Pair 2 is the same.
So, the strength of the magnetic force is the same in both pairs.


Question: Which trait did Ichthyornis have? Select the trait you can observe in the drawing.

Choices:
- fur
- a long neck

This drawing shows the skeleton of an ancient animal called Ichthyornis. This drawing was made by looking at the animal's fossils.

natural science

The way an organism looks or acts is called a trait. Scientists use fossils to learn more about the traits of ancient organisms.
Fossils can preserve the remains of body parts and activities. A fossil of a body part, such as a tail or a wing, can tell you what an organism looked like. A fossil of an organism's activities, such as a burrow or a footprint, can tell you about the organism's behavior.
Here are three examples of fossils and the traits that you can observe from them:
This is a fossil of an animal. This fossil tells you that the animal had a spiral-shaped shell.
This is a fossil of a plant. This fossil tells you that the plant had small leaves arranged in a branched pattern.
This is a fossil of an animal's footprint. This fossil tells you that the animal could walk on land.
An organism's fossil may not show all of the organism's traits. This is because most body parts are destroyed during fossil formation. When an organism's body turns into a fossil, only a few body parts are usually preserved.


Question: Based on the arrows, which of the following organisms is a decomposer?

Choices:
- earthworm
- bilberry

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

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:
Decomposers help break down dead organisms into simpler matter, such as nutrients. These nutrients can then help plants and other organisms grow. In a food web, there is an arrow pointing from another organism to a decomposer. There are no arrows pointing from a decomposer to another organism.
The earthworm does not have arrows pointing from it to other organisms. So, the earthworm is a decomposer.
The bilberry has arrows pointing from it. So, the bilberry is not a decomposer.


Question: What is the capital of Wisconsin?

Choices:
- Annapolis
- Lansing
- Madison
- Green Bay

social science

Solution: Madison is the capital of Wisconsin.


Question: Which ocean is highlighted?

Choices:
- the Pacific Ocean
- the Atlantic Ocean
- the Arctic 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 Arctic Ocean.


Question: Which of these states is farthest north?

Choices:
- Iowa
- Arizona
- Kansas
- Delaware

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. Iowa is farthest north.


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

Choices:
- platypus
- spectral tarsier

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

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 Atlantic puffin.
The Atlantic puffin has webbed feet. Its feet are adapted for swimming. As it swims, the Atlantic puffin uses its webbed feet to push itself through water.
Now look at each animal. Figure out which animal has a similar adaptation.
The platypus has webbed feet. Its feet are adapted for swimming.
The spectral tarsier has long fingers. Its feet are not adapted for swimming. The spectral tarsier uses its feet for climbing trees.


Question: Which continent was involved in the Seven Years' War?

Choices:
- Asia
- Australia

The French and Indian War took place in North America in the 1750s and 1760s. That war was part of a much larger conflict known as the Seven Years' War. The map below highlights the countries and territories that fought in the Seven Years' War. Use the map to answer the question below.

social science

Causes of the American Revolution: the French and Indian War

Solution:
Look at the map.
The map shows that the conflict involved countries and territories throughout Asia, South America, North America, Europe, and Africa. The only continents not involved were Australia, where no Europeans had settled, and Antarctica, where no humans lived.
The French and Indian War was part of a global war between rival empires. An empire is a group of places ruled by a central power. At the time, several empires were fighting to become the most powerful in the world. Many historians call this global war the Seven Years' War.
The French and Indian War was the part of the Seven Years' War fought in North America. This war led to big changes in the relationship between the Thirteen Colonies and Great Britain. Historians often consider these changes important causes of the American Revolution, which started less than 20 years later.


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

Choices:
- The strength of the magnetic force is the same in both pairs.
- The magnetic force is weaker in Pair 2.
- The magnetic force is weaker 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 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 weaker when the magnets are farther apart.

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


Question: Which of these states is farthest east?

Choices:
- Nebraska
- Kentucky
- Arkansas
- New Mexico

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. Kentucky is farthest east.


Question: What is the capital of Ohio?

Choices:
- Columbus
- Cleveland
- Des Moines
- Springfield

social science

Solution: Columbus is the capital of Ohio.


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

Choices:
- New York City
- San Antonio
- Denver
- St. Louis

social science

Solution: The city is St. Louis, Missouri. San Antonio, New York City, and Denver are marked with gray circles on the map below.


Question: Which animal's skin is better adapted for protection against a predator with sharp teeth?

Choices:
- Grant's gazelle
- nine-banded armadillo

Giant pangolins are adapted to defend their bodies against a predator with sharp teeth. They have hard scales covering much of their skin. When frightened, the  can roll into a ball to protect the soft parts of its body.
Figure: giant pangolin.

natural science

Animal adaptations: skins and body coverings

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors.
The color, texture, and covering of an animal's skin are examples of adaptations. Animals' skins can be adapted in different ways. For example, skin with thick fur might help an animal stay warm. Skin with sharp spines might help an animal defend itself against predators.

Solution:
Look at the picture of the giant pangolin.
The giant pangolin has hard scales on its skin. Its skin is adapted for protection against a predator with sharp teeth. The scales make it difficult for predators to hurt or kill the giant pangolin.
Now look at each animal. Figure out which animal has a similar adaptation.
The nine-banded armadillo has hard scales on its skin. Its skin is adapted for protection against a predator with sharp teeth.
The Grant's gazelle has short fur covering its skin. Its skin is not adapted for protection against predators with sharp teeth.


Question: A baby blue whale is as big as ().

Choices:
- an adult whale
- a car
- two buses

Read the first part of the passage about blue whales.
A blue whale is big. It is the biggest animal in the world.
When a blue whale is a new baby, it is as big as a car. When it is older, it is even bigger. It is as long as two school buses put together.
Complete the sentence.

language science

Solution: The passage says a blue whale is big. The passage says that when a blue whale is a new baby, it is as big as a car.


Question: In this experiment, which were part of a control group?

Choices:
- the yards with empty feeders
- the yards with feeders filled with sunflower seeds

The passage below describes an experiment.

Jason and his neighbors wanted to attract more woodpeckers to their yards. They read that woodpeckers often eat sunflower seeds. The neighbors wanted to find out if filling their bird feeders with sunflower seeds would increase the number of woodpeckers that visited their yards.
So, four of the neighbors filled their feeders with sunflower seeds. Another four neighbors left their feeders empty. Every morning for a month, the neighbors counted the number of woodpeckers they saw in their yards.
Figure: a woodpecker at a bird feeder.

natural science

Identify control and experimental groups

Experiments have variables, or parts that change. You can design an experiment to investigate whether changing a variable between different groups has a specific outcome.
For example, imagine you want to find out whether adding fertilizer to soil affects the height of pea plants. You could investigate this question with the following experiment:
You grow one group of pea plants in soil with fertilizer and measure the height of the plants. This group shows you what happens when fertilizer is added to soil. Since fertilizer is the variable whose effect you are investigating, this group is an experimental group.
You grow another group of pea plants in soil without fertilizer and measure the height of the plants. Since this group shows you what happens when fertilizer is not added to the soil, it is a control group.
By comparing the results from the experimental group to the results from the control group, you can conclude whether adding fertilizer to the soil affects pea plant height.

Solution: In this experiment, Jason and his neighbors investigated whether adding sunflower seeds to bird feeders affects how many woodpeckers visit yards. The yards with empty feeders did not get sunflower seeds. So, they were part of a control group.


Question: What is the capital of Maine?

Choices:
- Dover
- Augusta
- Albany
- Portland

social science

Identify state capitals of the Northeast

Solution: Augusta is the capital of Maine.


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


Question: Is a ballet shoe a solid, a liquid, or a gas?

Choices:
- a solid
- a gas
- a liquid

natural science

Classify matter as solid, liquid, or gas

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

Solution:
A ballet shoe is a solid. A solid has a size and shape of its own.
When a dancer wears a ballet shoe, it may bend a little. But the ballet shoe still has a size and shape of its own.


Question: Which country is highlighted?

Choices:
- Antigua and Barbuda
- Jamaica
- Saint Lucia
- Saint Kitts and Nevis

social science

Identify and select countries of the Caribbean

Solution: This country is Saint Kitts and Nevis.


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

Choices:
- each vial . . . the surroundings
- the surroundings . . . each vial

Scientists in a laboratory were working with insulin, a protein often used to treat diabetes. They left two identical vials of insulin in different places. This table shows how the temperature of each vial changed over 15minutes.

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 vial increased, which means that the thermal energy of each vial increased. So, thermal energy was transferred from the surroundings to each vial.


Question: What is the capital of Maryland?

Choices:
- Birmingham
- Frankfort
- Annapolis
- Baltimore

social science

Identify state capitals of the Northeast

Solution: Annapolis is the capital of Maryland.


Question: Select the mammal below.

Choices:
- bull shark
- yak
- shoebill
- eastern newt

Mammals have hair or fur and feed their young milk.
Mammals are warm-blooded. Warm-blooded animals can control their body temperature.
A giraffe is an example of a mammal.

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 bull shark is a fish. It lives underwater. It has fins, not limbs.
Bull sharks can live in both fresh and salt water. They are found in rivers and in shallow parts of the ocean.
A shoebill is a bird. It has feathers, two wings, and a beak.
Shoebills live in tropical East Africa. Shoebills get their name from their shoe-shaped beaks.
A yak is a mammal. It has hair and feeds its young milk.
Yaks live in cold places. Their long hair helps keep them warm.
An eastern newt is an amphibian. It has moist skin and begins its life in water.
Some newts live in water. Other newts live on land but lay their eggs in water.


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

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

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

Brody 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. Brody 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: What can happen to spores after they are released?

Choices:
- They can fuse and form a fertilized egg.
- They can grow into 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:
Unlike sperm and eggs, spores do not fuse.
After they are released, spores can land on the ground and germinate. When a spore germinates, it grows into a heart-shaped plant.


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


Question: What is the probability that a sheep produced by this cross will be homozygous dominant for the wool color gene?

Choices:
- 2/4
- 1/4
- 0/4
- 3/4
- 4/4

In a group of sheep, some individuals have white wool and others have black wool. In this group, the gene for the wool color trait has two alleles. The allele for white wool (L) is dominant over the allele for black wool (l).
This Punnett square shows a cross between two sheep.

natural science

Use Punnett squares to calculate probabilities of offspring types

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


Question: Which continent is highlighted?

Choices:
- Australia
- Asia
- Africa
- North America

social science

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

Solution: This continent is Africa.


Question: Which of these continents does the equator intersect?

Choices:
- Australia
- Europe
- Africa

social science

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

Solution: The equator is the line at 0° latitude. It intersects Africa. It does not intersect Australia or Europe.