This summer was especially challenging to keep the boys busy. In grade 4 the kids learned the basic of circuit, gears and forms of energy. I was looking for some creative toy to enhance the basic science when I chanced upon this solar car at http://www.sunwindsolar.com/.
I bought the SolarDrive Car and Inventor's Kit Version but I am sure the other versions must be equally good. The kit arrived in couple of weeks as promised. The kit does not have any pretty packaging and all the material is put together in a ziploc bag. If you ignore the marketing aspects, it is a good kit consisting of a solar cell, a motor with a gear, simple wheels, a body and some Velcro and screws to hold the car together. The assembly is easy enough for a 9 to 10 year old to put together with minimum help. The car operates beautifully in the sun as the solar cell powers the motor.
The parts can be reused to build several designs of solar cars, and experiment with different sized pulleys. The pulleys, drive-tires, shafts, and motor bushings (which fit onto the motor shaft and into the hub of any size pulley) provide the imaginative student with opportunities to construct other solar-driven machines. Screw eye axle-holders and wooden dowel axles allow axle-shafts to be mounted onto most materials at any angle. The solar panel and motor are easily detachable for further experimentation.
Now, ever since we built that car, it has been raining continuously for 5 days and now we are waiting for some solar energy to play with the car. This also nicely introduces the pitfalls of relying too much on the solar energy.