Make four long slits on each side of the cork to insert the base of the blades. Then add glue to re-enforce the blades. This will prevent them from slipping out of the slits when the force of the water pushes on them.
Drill a hole through the middle of the cork and insert the wood dowel. Affix, the dowel to the cork using your waterproof glue. Now make two holes on either side of your second soda bottle where the wooden dowel will rest. They should be approximately four inches from the top. Cut a slit large enough to insert your fan inside the bottle. Make sure the sides of your fan are not too long and touch the sides of the soda bottle when the dowel turns. We taped the slit closed once the fan was inside the water bottle so our water would not escape.
Place the funnel in the top of the soda bottle. Watch the force of the water turn the fan and the outside dial (cream cheese top). We colored our water with a little food coloring so it would be easy to see. We followed up this activity discussing different types of turbines (gas, air, water). What makes a turbine useful, and how it makes work easier. Have fun with this cheap science experiment. It is a great way to recycle house hold items.