How to Make a Balloon Powered Model Car

Drill a hole in the middle of each milk jug cap just big enough to accommodate the skewers. Tape a straight straw along each short side of the cardboard. Thread a cap onto one end of a skewer. Slip the opposite end through one of the straws, and attach another cap onto the other end of the skewer. Repeat with second sewer and remaining caps.

Blow up the balloon and let the air out two or three times to stretch it. Cut the bendable straw so that the long end is the same length as the short end. Slip one end into the mouth of the balloon and secure with the rubber band.

Place the other end of the bendable straw so that the end of it hangs over one short edge of the top of the cardboard car. Tape the straw in place, so that the balloon extends across the length of the car.

Blow up the balloon through the straw. Holding a thumb over the opening, place the car on it's wheels on a smooth surface, and release the straw. The air pressure releasing from the balloon will power the car.