The focus is that matter, whether solid, liquid, or gas, is made up of particles; that dissolving and evaporation happen at the particle level; and that models can help explain these processes that we ...

Solids, liquids and gases. In a solid like this brick ... and the number of spoonfuls of cornflour or custard powder. Try this activity five times but change one variable each time.

Through investigating solids, liquids, and gases and the phenomena of dissolving, evaporation, and condensation, students develop models to investigate matter at the particle level.