All matter contains tiny particles, and the way these particles behave is different in different states of matter. Learn the differences between solids, liquids and gases, with reference to the particle model of matter.

Matter can change between solid, liquid and gas when it is heated up or cooled down: a transfer of heat energy. Learn how water changes state, through melting, evaporation or boiling, freezing, sublimation and deposition.

Matter changes state by adding or taking away heat energy. But what happens to the energy and temperature when the state of matter changes? Explore latent heat and the water cycle when water on Earth changes state.

Substances are affected by changing their temperature, even if there is no change of state. Learn how matter can expand or contract when heat energy is transferred, and why water is such a unique substance.

Everyday we make use of the physical properties of matter. Explore some common examples of how humans use physical changes of state for many purposes, including steam engines, antifreeze, distillation and hydraulic systems.