States of Matter

Grade 2 · Science · Study Guide

Learn about the three states of matter — solid, liquid, and gas — and how matter can change between them.

Everything around you — your desk, the water in your glass, the air you breathe — is made of matter. Matter is anything that takes up space and has weight. All matter exists in one of three main states: solid, liquid, or gas.

A solid has a definite shape and size. It does not change shape on its own. Rocks, ice, and books are solids. A liquid does not have its own shape — it takes the shape of whatever container it is poured into. Water, juice, and honey are liquids. A gas does not have a shape or a set size. It spreads out to fill any space it is in. The air around you and the steam from hot soup are gases.

Matter can change from one state to another when heated or cooled. When ice (a solid) is heated, it melts into water (a liquid). When water is heated even more, it evaporates into steam (a gas). When steam cools down, it condenses back into liquid water. And when water gets very cold, it freezes back into ice.

These changes happen all around us every day!

Key terms

Matter
Anything that takes up space and has weight.
Solid
A state of matter with a definite shape and size, like ice or a rock.
Liquid
A state of matter that flows and takes the shape of its container, like water.
Gas
A state of matter with no fixed shape or size that spreads to fill its container, like air.
Melting
When a solid is heated and turns into a liquid.
Freezing
When a liquid is cooled and turns into a solid.

Flashcards

Solid
Has its own shape and size. Example: ice cube, rock, wooden block.
Liquid
Flows and takes the shape of its container. Example: water, milk, juice.
Gas
Spreads out to fill any space. Example: air, steam, helium in a balloon.
Melting
A solid turns into a liquid when heated. Ice melts into water.
Freezing
A liquid turns into a solid when cooled. Water freezes into ice.
Evaporation
A liquid turns into a gas when heated. Water evaporates into steam.
Condensation
A gas turns into a liquid when cooled. Steam condenses into water droplets.

Questions

  1. Which of these is a solid?

    1. Juice
    2. Steam
    3. Rock
    4. Milk
    Show answer

    Answer: Rock

    A rock has a definite shape and size, which makes it a solid. Juice and milk are liquids, and steam is a gas.

  2. A liquid takes the shape of its container.

    Show answer

    Answer: True

    Liquids flow and take the shape of whatever container they are in. Pour water into a cup and it becomes cup-shaped.

  3. What happens to ice when it is heated?

    1. It becomes a gas.
    2. It becomes a liquid.
    3. It becomes bigger.
    4. Nothing changes.
    Show answer

    Answer: It becomes a liquid.

    When ice (a solid) is heated, it melts and becomes water (a liquid). This change is called melting.

  4. Air is an example of a ___.

    Show answer

    Answer: gas

    Air has no fixed shape or size and spreads to fill any space, which means it is a gas.

  5. When water freezes, it turns into:

    1. steam
    2. juice
    3. ice
    4. rain
    Show answer

    Answer: ice

    When water gets very cold, it freezes and becomes ice, which is a solid.

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