Compare and group materials together, according to whether they are solids, liquids or gases. Observe that some materials change state when they are heated or cooled; identify the part played by evaporation and condensation in the water cycle. Know that some materials dissolve in liquid to form a solution, and describe how to recover a substance form a solution.
 
Use knowledge of solids, liquids and gases to decide how mixtures might be separated, including through filtering, sieving and evaporating; demonstrate that dissolving, mixing and changes of state are reversible changes; explain that some changes result in the formation of new materials, and that this is not usually reversible.