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Birds are found all over the world. Some, like penguins, live in cold places while others, like toucans, live in tropical climates. All birds have wings, which most use for flying. Some birds don't fly but use their wings as flippers for swimming or have strong legs for running. All birds have feathers, lay eggs, and have hollow bones to make them lighter so they can fly. Most birds live on land and some spend most of their time in water. Bird...

A mammal is an animal that breathes air, feeds milk to its babies, and has fur for at least part of its life. Most mammals give birth to live babies. Only a few lay eggs. Some mammals, like cows and goats, are herbivores and eat only grass and other plants. Others, like cats, are carnivores and eat only meat. Some mammals, like whales, live only in the ocean, and others, like squirrels and bobcats, live only on land. Some mammals, like beavers...

Whales are animals that live only in water. Most whales live in oceans, but a few live in rivers. Whales are mammals, animals that breathe air, feed milk to their babies, and have fur for at least part of their life. Most mammals give birth to live babies. Whales are in a group of mammals called cetaceans. Cetaceans spend all their time in water and take in air through blowholes on top of the head. They must come to the surface frequently to b...

A platypus has a bill like a duck, lays eggs like a duck, and has webbed feet. It has a flat tail and fur like a beaver. This unusual animal belongs to a group of mammals called monotremes. A mammal is an animal that breathes air, feeds milk to its babies, and has fur for at least part of its life. Most mammals give birth to live babies, with monotremes being the only egg-laying mammals. Platypuses live near lakes and slow-moving rivers. They ...

Fish are animals that swim in water and are found in lakes, rivers, streams, and oceans. There are three types of fish: bony fish, cartilage fish, and fish without jaws. Bony fish, such as bass, are the most common and are named for their skeletons which are made of bones. Bony fish have a swim bladder that allows them to adjust their depth in the water by putting more air in the bladder to rise or releasing some air to sink. Cartilage fish, s...

Worms are animals that have long bodies and no legs. They live on land, in the ocean, and sometimes in other animals. There are three groups of worms: segmented worms, roundworms, and flatworms. A roundworm is shaped like a long round tube, while flatworms have flat bodies and are sometimes brightly colored with different patterns. Segmented worms look like they are made of many small pieces. Earthworms eat dead plants and animals and make foo...

Earth has different parts that work together to keep Earth in balance. The geosphere is the rocky part of Earth. The atmosphere contains all the air. The biosphere is made of all the living things. The hydrosphere consists of all the liquid water, snow, and ice. The magnetosphere includes the magnetic field surrounding Earth. All of these parts are needed for life to exist. Rain and snow in the hydrosphere give water to plants and animals. Pla...

A star is an object in space made of hydrogen and helium atoms. It makes its own light energy and heat energy when hydrogen atoms combine to make helium. (Atoms are described.) Stars are born inside a huge cloud of gas and dust and die when they run out of the hydrogen they use for fuel. A big star that runs out of fuel ends its life in a huge, very bright explosion called a supernova and leaves behind a cloud of gas and dust called a nebula. ...

A black hole is an object in space that cannot be seen because it sucks in everything near it, including light. It looks like a totally black area in space because no light escapes from it or bounces off it. Astronomers learn about black holes by observing the materials swirling around them and what happens to these materials. A black hole has a huge amount of gravity that pulls materials into it. A black hole can form when a big star reaches ...

Bats are a type of mammal and the only mammal that flies. Mammals are animals that breathe air, feed milk to their babies, and have fur for at least part of their life. Most give birth to live babies. During the day, bats sleep upside down in protected places. At night some bats fly around catching bugs to eat. Other bats eat fruit, plant parts, and nectar from flowers. Baby bats are called pups and hold onto their mother as she flies around t...

A galaxy is a huge group of stars, planets, gas, dust, comets, asteroids, and other objects in space. Our Sun and Earth are part of the Milky Way Galaxy. The Milky Way is so huge that we cannot travel outside it to see what it looks like. Studying other galaxies and how stars are arranged in the Milky Way gives astronomers an idea of what it looks like. Telescopes are instruments used to study galaxies and other objects in space. Scientists th...

biology, elementary science, life science, home school, Real Science-4-Kids, gastropod, bivalve, cephalopod, mollusk, Mollusca, radulaSnails are a type of mollusk. Mollusks are in the scientific group Mollusca and are soft-bodied animals that live in oceans and lakes and on land. The three types of mollusks are gastropods (snails and slugs), bivalves (clams and oysters), and cephalopods (octopuses and squids). All mollusks have organs and a ma...

Astronomers use various types of telescopes to study faraway objects in space. Telescopes are tools that make distant objects look bigger, and space telescopes are in orbit high above Earth. The Hubble Space Telescope has taken over a million photos of objects in space, and some of these are nebulae. A nebula is a huge cloud of gas and dust that swirls to make beautiful cosmic art. Some nebulae are areas in space where new stars are formed. So...

A planet is an object in space that orbits a star, is spherical, and is big enough to have its own gravity. Earth is one of 8 planets that orbit the Sun. There are two different types of planets. Terrestrial planets are Earth-like and made of rock. Mercury, Venus, Earth, and Mars are terrestrial planets and are closest to the Sun. Jovian planets are Jupiter-like and made of gas. Jupiter, Saturn, Uranus, and Neptune are Jovian planets and are f...

A constellation is a group of stars that forms a shape and has been given a name. Different constellations can be seen from the Northern Hemisphere and the Southern Hemisphere. From the equator all the constellations can be seen. The Big Dipper and Cassiopeia are Northern Hemisphere constellations, while the Great Square, Pegasus, and the Southern Cross are seen from the Southern Hemisphere. The Big Dipper points to Polaris, which is also call...

The Moon is spherical and much smaller than Earth. It is made of rocks and minerals, like Earth, but has very little air and no liquid water but some ice. The Moon doesn't make its own light but rather reflects light from the Sun, and it orbits the Earth, completing one orbit every month. The Moon looks different from day to day as it moves in its orbit around the Sun. It can look completely round, half-round, or crescent-shaped. The light and...

Astronomy is the study of stars and other objects in space. Ancient peoples studied the sky and the movement of stars, the Moon, and the Sun and were able to create calendars based on their observations. These early astronomers also named individual stars and groups of stars. Since astronomers can't travel to stars and other distant objects, they use tools to study these objects. The telescope is a tool used to see deep into space. One type of...

Earth is part of a solar system, which is made of a star and the group of planets and other objects that orbit a star. The Sun is a star and is the center of our solar system. A star is an object in space that make its own light and heat energy. Our solar system contains eight planets, an asteroid belt, and moons around the planets. The inner solar system consists of the first four planets orbiting the Sun: Mercury, Venus, Earth, and Mars. The...

Earth is a planet because it is an object in space big enough to have its own gravity, is spherical, and moves around a sun. Earth moves in an almost circular orbit around the Sun. It also rotates around an axis, an imaginary line that goes through its center. Earth's rotation around its axis causes day and night, with one day being one full rotation of Earth. Earth's axis is tilted with respect to the Sun, and the combination of the tilt of E...

The Sun is a star that gives Earth heat and light. There are even more stars than those we can see in the sky. Stars are objects in space that are made of hydrogen and helium gas that make heat and light energy when hydrogen atoms combine to make helium. (Atoms and matter are defined.) Stars are different sizes, both smaller and larger than the Sun. Proxima Centauri, Alpha Centauri A, and Alpha Centauri B are the stars closest to Earth. Proxim...