Students will write a summary statement of the 3 variables that are important for the flight of a rocket motor. Students will construct a balloon rocket and race them along a guide wire. Tell the class that this is a rocket and you are going to 'fly' it. Release the end which you have pinched off and the balloon will snake off, slithering in random directions. A discovery of the Chinese is that the stick will give a rocket directional stability.
Modern rockets use fins.
Here I have a rocket toy. Point out the fins. It works by fitting the nozzle over the tip of this pump and pumping some air into the rocket. Release the rocket. Let me put some water in the rocket first.