Many of the common everyday materials around us can be grouped as solids or liquids.

Liquids take the shape of their container, they have a flat surface and they can be poured, like this orange squash.

Solids, like this coin, have a definite shape and take up a definite amount of space (or volume).

This pile of sand is made of small, hard pieces, that are solids.

As you can see, it does not have a flat surface, but often flows back if you push your finger into it - so, is sand a liquid?!

OK, let's get stuck into solids and liquids...