A pinwheel model of a turbine
Scientists build models because a power station is too big to take into the classroom. A pinwheel on a stick is a good model of a turbine. If you pour water from a jug onto the pinwheel, the water pushes the blades and the pinwheel spins, just as water pushes a turbine in a dam. The jug stands for the water stored behind the dam, and the bin stands for the river below. This model does not make electricity, but it shows the first part of the chain. When the jug is empty, the water is in the bin. If you scoop it up with a cup and pour it back, you can use it again. In nature the Sun does this job: it warms the sea, water rises as vapour, clouds form, rain fills the rivers and the dam is refilled. That is why water power is renewable. Wind and moving water are both sources of mechanical energy.
| In the model | In a real power station |
|---|---|
| jug of water | water stored behind the dam |
| pinwheel | turbine |
| bin | river below the dam |
| scooping with a cup | rain refilling the river |
Build the model (a grown-up helps). Do it outside or over a big tray. You need a pinwheel on a stick, a plastic jug, a cup and a bin. Hold the pinwheel over the bin and pour the water on the blades. Does it spin? Try a slow pour and a fast pour. Then scoop the water with the cup and use it again. Draw your model with labels. Wipe up spills so nobody slips.