A paper plate with ridges along the edges
A water tap
Take the pencil and push it through the centre of the plate. Make sure the pencil is properly hooked through the plate and the hole is neither too big, nor too small, but loose enough for the plate to move.
Now, open the water tap and bring the ridges of the plate in contact with the water.
You will see that the plate moves round and round. Increase the flow of water and you will see that the plate will move even faster.
How does this work?
You have just formed a waterwheel. In industries, water is used to generate electricity. The water hits the turbine, which is modelled on the waterwheel. Greater the force of the water, faster the turbine moves, which in the end generates electricity.