Ball and Hoop

We use a metal ball and hoop to demonstrate heat expansion. When cool, the ball fits through the hoop, but there is little extra space. The ball is then heated over a Bunsen burner. When hot, the ball doesn't fit through the hoop. We see how the size of the metal ball changes as it is heated.

Physics - Energy And Radioactivity - Learning Points.
Metals expand when heated.
For small objects, the expansion is hard to see with the naked eye, but it can be important in precision-engineered parts.
For large objects such as bridge decks, the expansion is large enough to see.

A Twig Experiment Film.
Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.