We're starting a brand-new topic: how materials change. Some changes you can undo… and some you can't. Today is about the ones you can reverse.

Everything around us is made of tiny particles. Whether something is a solid, liquid or gas depends on how those particles are arranged — and heating gives them energy to move.

A reversible change changes how a material looks, but it's still the same substance — and you can get the original back.

Change	What happens	Temperature (water)
Melting	solid → liquid	0°C
Freezing	liquid → solid	0°C
Boiling / evaporating	liquid → gas	100°C
Condensing	gas → liquid	100°C

Watch closely: I'll stir sugar into warm water. The sugar seems to vanish… but has it really gone?

Now we investigate together. You'll rotate through three stations and record what you see.

Station	What to do	Question to answer
1. Melting	Watch ice / chocolate under the lamp	Can it become solid again?
2. Dissolving	Stir sugar or salt into warm water	Where did it go? Is it still there?
3. Evaporating	Discuss the salt-water dish left to dry	What will be left behind?

On your own, complete the observation sheet for each station.

"Melting is a reversible change because the ___________ is still the same."

Quick check before we finish…