They may notice the solid bottle, the liquid drink and the gas both within the drink and at the top of the bottle. Now ask them to predict how much gas they think is in the bottle in millilitres.

After viewing a model of salt, students help develop models for the processes of salt dissolving, water evaporating to form a gas, and salt re-forming as a crystal. The focus is that matter, whether ...

It turns out that any material, no matter what it is made of, can exist in one of three forms: solid, liquid or gas. These are categories of stuff that have certain observable properties.

JOE:So how does it work? SEGE:'Well you see Joe, normally when substances heat up they transform from a solid and then a liquid before turning into a gas. 'Think about a regular ice cube melting.