* Water freezing into ice: The chemical composition of water (H₂O) remains the same, but its physical state changes from liquid to solid.
* Boiling water: The water changes from liquid to gas (steam), but it's still H₂O.
* Cutting a piece of paper: The paper is divided into smaller pieces, but its chemical makeup remains the same.
* Melting a chocolate bar: The chocolate changes from a solid to a liquid, but it's still the same chemical compound.
* Crushing a can: The can changes shape, but the aluminum it's made of remains the same.
Key takeaway: In a physical change, the substance's chemical composition doesn't change. It only changes its form or appearance.
