When matter undergoes a physical change, its appearance or form changes, but its chemical composition remains the same. This means the molecules that make up the matter don't change, just their arrangement or state.

Here's an example:

Ice melting into water:

* Physical Change: The ice changes from a solid to a liquid.

* Appearance change: Solid ice is hard and opaque, while liquid water is fluid and transparent.

* Chemical composition: Both ice and water are made up of the same molecule, H₂O. The molecules haven't changed, just their arrangement.

Here are some other examples of physical changes:

* Boiling water: The water changes from a liquid to a gas (steam).

* Freezing water: The water changes from a liquid to a solid (ice).

* Cutting paper: The paper is divided into smaller pieces, but the paper itself is still paper.

* Crushing a can: The can is deformed, but it's still made of the same metal.

Important Note: Physical changes are usually reversible. For example, you can freeze water back into ice.