We use water to turn wheels to make electricity (hydroelectricity), catch fish (fish wheel) or grind flour.
Pour water over a wheel to show how it turns.
Optionally lift an object from the floor to the table top, using the force of falling water on the water wheel.
Before the class, prepare discs from the pie plates for the students, as cut edges are sharp:
Carefully cut out the flat part of the pie plate and discard the sides.
Punch a hole exactly in the centre with a pencil and enlarge slightly.
Students make cuts from the edge of the pie pan 2/3 of the way to the centre, in four or six places (to start, try modifications later). Fold over the sides of each section to make a paddle wheel shape.
Wrap a small piece of foam around the wooden rod and tape it in place. Push the rod through the hole in the pie plate, enlarging the hole until the plate fits snugly on the foam around the rod. The plate should not turn easily at all without the rod (the axle) turning.
Tape U-shaped pieces of foam to the centre of each of the long sides of the tray.
Lay the wheel and axle over the foam supports on the tray. Test that it can turn without hitting the bottom of the tray. If necessary, fold over the outside edges of the pie plate.
If objects are to be lifted with the falling water, make sure one end of the rod protrudes over the edge of the tray more, then tape the string to this end of the rod. Cut the string off where it meets the floor, and tie on a small weight e.g. the scissors.
Pour water from the 2L bottle onto the wheel. The weight of the water hitting the paddle blades generates a force which makes the blades move and the wheel turn.
Once the water runs out, pour the tray of water back into the bottle (using the funnel) for reuse.
If a weight is being lifted, the turning wheel turns the rod, which winds the string and pulls up the weight.
Challenge student to control how they pour the water to make the weight raise slowly or faster.
In a traditional water mill, a water wheel turns grindstones to make flour:
A fish wheel turns in the moving water of a river and has attached netting to catch salmon:
Fish wheels are used to catch salmon during a run, either for food or for tagging (to track salmon populations).
Hydroelectric power is made from a water wheel (called a turbine):