To make a balloon powered car, the first step is to make a car body on which to mount the balloon. The video below shows one way to make such a car, using a skewer that is attached tightly to the wheel and a straw as a bearing.
If the wheels fit loosely on the axle, then the axle may be taped directly to the cardboard and the wheels will still turn on the axle. In this case students must find a way to keep the wheels on the axle while still allowing the wheels to turn freely.
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