Science & space · 3–4
States of matter
Matter is anything that takes up space. Solids keep their shape, liquids flow to fit their container, and gases spread out to fill the available space.
Quick review
Key points to remember
- A solid has a fixed shape and volume.
- A liquid has a fixed volume but changes shape.
- A gas has no fixed shape or volume.
- Heating and cooling can change matter’s state.
Useful words
Topic vocabulary
- Melting
- A solid changing into a liquid.
- Freezing
- A liquid changing into a solid.
- Evaporation
- A liquid changing into a gas at its surface.
- Condensation
- A gas changing into a liquid.