Next, push each dowel through one of the straws on the bottom of the box. Then attach the other two bottle tops onto the other ends of the dowels.

This is the base of your vehicle. The front wheels (on one axle) move independently of the back wheels, but the vehicle is difficult to steer, as all of the wheels do not move independently.

Can you design and make a car with four wheels that all turn independently so that the vehicle can be steered?