1) Colour some water (using food colouring) and freeze it in containers – balloons work well.
2) When frozen, take the ice out of the balloons / containers and put them in a water trough.
3) Allow the children to feel the ice and discuss it, as well as discuss the colour mixing which takes place. The results of the colour mixing could then be used in their artwork when mixing paints.
This activity could also be used as the stimulus for further work on how materials (in this case, water) change when heated or cooled.
Although the age range 5-7 is specified, this activity is great for all ages really – a fun, hot day learning experience.