Science Glossary
Science Glossary

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acid rain
Rain that contains chemical pollutants and can harm living and nonliving things.
Acid rain has made the lake's water poisonous and is harming the fish.

Animal with smooth, moist skin; it has gills when young and then develops lungs when older.
Frogs, toads, and salamanders are amphibians.

A living thing that can move from place to place, has a body covering, and eats other animals or plants for food.
Monkeys and ocelots are two kinds of animals found in a tropical rain forest.

A type of protective covering for the body.
A hard covering of armor could protect a dinosaur from sharp teeth.

The study of space and the heavenly bodies.
Galileo's study of Earth's orbit around the sun is astronomy.


beaver dam
A wall built by a beaver to hold back flowing water.
A beaver dam is made with cut trees, stones, and mud.

A two-legged animal with feathers and wings.
A bird is the only animal that has feathers covering its body.

To rebound from a surface.
A ping pong ball will bounce higher than a baseball.


The top layer of the rain forest formed by dense leaf-covered tree branches.
Monkeys peered down at us from the canopy.

A pupa (the stage between a larva and an adult) enclosed in a firm case or cocoon.
The chrysalis was pale gray and about an inch long.

A mass of tiny droplets of water that condensed from the air.
A dark cloud blocked the sunlight.

cool down
Movements done to slow the heart and relax the muscles after exercising.
The runner walked to cool down after the race.

The change in form water goes through when it turns from a gas to a liquid.
The condensation on the windows ran down and made the windowsill wet.

To keep and protect from harm, loss, or change.
Let's conserve our drinking water so that we don't run out.


One of a large group of reptiles that lived millions of years ago.
All dinosaurs lived on land.

The course taken by a moving body.
Putting the car in reverse will change its direction.

Toward the ground.
The bicycle rolled down the hill.


All the living and nonliving things that are around a living thing.
A drop of water, a rotting log, and a forest are different kinds of environments.

The change in form that water goes through when it turns from a liquid to a gas.
As you boil water, it evaporates and becomes a gas.

Moving the body.
Walking fast is good exercise.

When all animals of one kind die; no longer existing as a species.
There are no dinosaurs today because these animals are extinct.


A giant crack in a rock that makes up the Earth's surface.
A shift along the fault line caused the earthquake.

Body covering of birds.
Feathers keep a bird warm.

An animal that lives in water that has gills for breathing and fins for swimming.
Many fish have scales as a body covering.

flat teeth
Teeth that are good for grinding food.
Most plant-eating dinosaurs had flat teeth.

The part of a plant from which seeds can develop.
This flower has a bright red blossom and a sweet smell.

fossil remains
What is left of a plant or an animal that lived long ago.
Scientists study fossil remains to learn more about dinosaurs.


A form of matter that can move about freely and does not have a definite shape.
Water vapor is a gas and can move through Earth's atmosphere.

good health habits
Habits that help a person to stay well.
Getting enough rest and exercise are good health habits.

The force that causes an object to fall to earth.
When you jump up, gravity will bring you back down to earth.


A place in which a plant or an animal lives.
A living thing gets all the things it needs to stay alive from its habitat.

Body covering of mammals.
Hair helps mammals stay warm and protects their skin.

Body part that pumps blood throughout the body.
Put your hand on your heart and feel it beat.

hinged jaws
Jaws joined with a hinge-like joint so they open wide.
Hinged jaws let some dinosaurs swallow huge chunks of meat.

hollow tube
A tube with an empty space within it.
Some dinosaurs may have used the hollow tubes on their heads to make sounds.


An animal with three main body parts and six legs.
Ants are one kind of insect found in the rain forest.




The thin, flat green part of a plant that grows on a stem.
Leaves make food for a plant.

A form of matter that can flow easily and takes on the shape of any container into which it is poured.
A liquid like milk can be poured from a square milk carton into a round glass.

living thing
Something that is alive and can grow.
Living things need food, water, and air.


An animal that is covered with hair and feeds milk to its babies.
Dogs and cats are mammals that make good pets.

A small plant that has bright yellow or orange flowers with a strong smell.
Gardeners sometimes plant marigolds because their smell helps to keep insects away from other plants.

The series of changes in shape and function that certain animals go through as they develop from an egg to an adult.
The metamorphosis of a tadpole to a frog changes that animal in many ways.

A plant or animal of microscopic size.
Diatoms and protozoa are two types of microbes.

Any living thing that is too small to be seen with the naked eye.
John was only able to see the water microorganisms by using the microscope.

A tool using one or more magnifying lenses to see things too small to see with the naked eye.
The bacterium is too small to be seen without a microscope.

To shed the hair, feathers, skin, or shell and grow a new covering.
The snake molted its old skin and left it behind.

To change place or position.
It is difficult to move a large box filled with books.

Body parts that help a person move.
Your leg muscles help you run.


natural resource
Materials that come from the earth and can be used by living things, for example: water, oil, and minerals.
One reason that trees are an important natural resource is that their wood is used to build houses and to make paper.


objective lens
The lower lens in a microscope that is closest to what is being looked at.
She rotated the objective lens into position, just above the slide.

ocular lens
The upper lens or eyepiece of a microscope that the viewer looks through.
He kept both eyes open as he looked through the ocular lens.

The path that a planet or other heavenly body follows as it moves around the Sun or another heavenly body.
The moon orbits the Earth.


A living thing is green, and needs water, light, and air to grow.
Many rain forest plants have large leaves and tall stems.

1. A thin, flat piece of bone.
One dinosaur had a row of pointed plates running down its back.
2. A very large slab of rock that makes up the crust and mantle of the Earth.
The Himalayan Mountains were created when one plate collided with another plate.

pointed teeth
Sharp teeth that are good for tearing food.
Most meat-eating dinosaurs had pointed teeth.

Containing waste materials or other unwanted substances.
The river that runs through town is polluted.

A small body of water.
Fish and frogs often live in a pond.

The falling of water in the form of rain, sleet, hail, or snow.
During the last big winter storm, the precipitation took the form of snow and sleet.



To process and reuse materials.
Discarded newspapers are recycled to make new paper.

Type of music that came from the Caribbean region, and has a strong beat.
Many reggae tunes have a fast beat.

An animal that is cold-blooded, and has scaly skin, and creeps or crawls on the ground.
Snakes, turtles, and lizards are all reptiles.

To lie down or sit quietly; to give the muscles a break from working.
After you exercise, you should rest.

To move by turning over and over.
A round object like an orange will roll down a ramp.

round and round
A push-and-pull motion.
Wheels, tops, balls, and many other objects move in a round and round motion.


The part of a plant from which another plant can grow.
A coconut is a very large seed.

An instrument that measures and records the Earth's vibrations.
The seismograph indicated that an earthquake was coming.

A place where an animal can rest and be safe.
An animal stores food and raises its young in a shelter.

The surface layer of earth where plants grow.
Gardeners often wait until the soil is warm before planting seeds.

A form of matter that has shape and hardness.
An iceberg is one of the biggest examples of water in a solid form.

The rate at which something moves.
A bicyclist's speed usually drops when riding up a steep hill.

To make longer by pulling.
Before exercising, she will stretch and bend.

A tall plant that has a large yellow, orange, or brown flower with many large black seeds in its center.
One large sunflower may have several hundred large seeds.


theory of plate tectonics
The theory explaining that the Earth's plates, or large slabs of rock, are constantly moving, causing continents and oceans to form, be destroyed, and reform over very long periods of time.
The theory of plate tectonics explains what causes earthquakes.

A storm that produces lightning and thunder and often heavy rain and strong wind.
When the weather is hazy, hot, and humid, thunderstorms are likely to develop.

tropical rain forest
A type of rain forest where conditions are very warm and humid.
Many types of parrots live in tropical rain forests around the world.


The level of the rain forest just below the canopy.
Insects flew through the understory.

Toward the sky.
The ball flew high up in the sky before falling back to earth.



warm up
Movements done to get the body ready to exercise.
The runner stretched to warm up before the race.

water cycle
The path that water follows as it evaporates into the air, condenses into clouds, and returns to Earth as rain, snow, sleet, or hail.
After the sun's heat dried up the pond, water from rain filled it back up, completing its journey through the water cycle.

A round ring with spokes that is attached to objects to move them.
A tricycle has one more wheel than a bicycle.




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