This is a compilation of clips set to a background of music and based on the theme of changing materials. It includes images of fireworks exploding, demolition of tower blocks, a volcano and magma flowing, a time lapse sequence of a cake being baked, a candle melting, toffee in both liquid and solid form, melted metal being cast, a rusted metal sculpture, a match burning, wood, coal, a burning building and a forest fire. Reversible and irreversible changes are demonstrated. Note: There is no narration in this clip.

First broadcast:
11 October 2007

Ask children to provide their own commentaries for the clip, after they have watched it once or twice. Can they describe each of the onscreen changes? You may need to pause the playback from time to time to allow pupils more space to describe the changes they see. Encourage the children to use appropriate words to describe the materials, such as "rusty", "dusty" and "burnt". Pupils could go on to discover how simple, everyday materials are affected by heating or cooling. They could put an ice cube in a saucer on a sunny window sill for instance, or melt chocolate buttons by putting them in a plastic bag and holding the bag in a warm fist.