Inside the Earth it is very hot. Even rock will melt if it gets hot enough. Molten rock from a volcano is seen solidifying as it cools.

First broadcast:
9 October 2007

An example of how some solids turn to liquids when heated, the clip could be used as a stimulus to investigate whether all materials melt at the same temperature. Having watched the clip, pupils could be asked the question 'Do all solids melt at the same temperature?' Presented with a range of solids eg chocolate, ice, wax, the children could carry out an experiment (under supervision) to test this question, making predictions and analysing results to draw conclusions. Pupils should be encouraged to predict what will happen to the solids once cooled and draw parallels with the molten rock in the clip.