1. The Knitting Needle Experiment

When exposed to heat, (almost) every solid object expands. For example, a metal stick gets longer if it is heated. As soon as it cools down again, it shrinks back to its original length.

You can try it out for yourself! You can use a knitting needle as a metal stick and tealights as your source of heat.

Requirements:

• one knitting needle (alternatively: a metal skewer)
• tealights
• two glass bottles of the same height
• one cork
• a lighter or matches

How do we make the expansion best visible?