This is a spinning one demonstrating Newton's third law of motion: 'to every action there is an equal and opposite reaction.'
Mine (babes) had to hang on to it and jump from the quarry to see if they could levitate with it (ie using propulsion). :)
First gather up your supplies
Then blow up your balloon to stretch it out a bit
Let it deflate and tape your balloon to the long end of a flexible straw (very near the end).
Find the balance point
Prick your straw with the stickpin at the balance point, and stick the pin and straw into the eraser end of the pencil.
Send your straw spinning manually a few times to loosen the hole so that it will spin easily.
Blow up your balloon
and let it fly!!