Found at a yard sale this morning: a science kit from about 1990 called "Mechanics Kit," similar in concept to this kit but without the battery-run parts. It was designed by "Tree of Knowledge (1979) Kibbutz Yasur, Israel," and I think it's a very clever and versatile concept--especially for a quarter. I think this is something that Crayons could use for science next year.
It's all plastic; you get two sizes of wheels, some small plastic pins, a propeller, a chassis for a vehicle, a couple of triangular supports, and a few miscellaneous things. Using rubber bands and a balloon, you can turn the parts into various kinds of simple machines, make a rubber-band motor, build a wagon, demonstrate tensile strength, build a cantilever bridge using strips of cardboard, and more. I don't think the kit is still in production, though--too bad!