You use lots of materials every day. What happens when some of them are heated? Do they change? How? What's left?
For example, you know that when butter is heated in a pan it melts into a liquid.
You know that the metal pan itself doesn't change - it just gets hot. Metals need to get a great deal hotter to change - that makes them ideal for making saucepans.
If you took the pan off the heat and left it to cool, you expect to see the butter solidify back into solid butter - that's called freezing, even though it's still fairly warm!
What if you continued to heat the molten butter? It would boil and, if you kept on heating it change into a brown sticky mess!
So, in this worksheet there are several materials for you to think about and decide if they change and how they change. Here's another example: what happens when you heat a piece of bread? You get toast - yum!