Three objects are made from different pure metals. It is possible to determine the type of metal from the temperature at which the different metals start to melt. A pyrometer measures very high temperatures. The lead melts first, followed by the aluminium and finally the copper. At the foundry, metals are melted and poured into casts. When the liquid metal cools it solidifies again into the shape of the cast.

First broadcast:
9 October 2007

Could be used when learning about changing materials and properties of materials. Before showing the clip you could ask the children to predict how solid material can change when exposed to heat. After having shown the clip you could invite the children to find out about the melting point of other metals. Ask them to draw a thermometer and mark the melting points of all metals investigated. Is this change reversible?

You could explore the states of water with the help of an experiment, looking at its freezing and boiling point. How does water change when freezing or boiling? Are these changes reversible? Under what conditions? Perhaps invite the children to draw up a diagram of the states of water at different temperatures: solid, liquid, gas.