Gears
Materials
Procedure
1. Nail two bottle tops to a piece of wood so they can interlock with each other and act as gears.
2. Turn one lid and the other one touching it should turn as well. This is called a direct drive connection.
3. Separate the lids by a few centimetres and place a rubber band around them. Try turning one of the lids and the other should turn. This is called an indirect drive as a 'belt' is connecting the two gears.