This is intended to be a "fun" exercise (but don't hurt yourselves) and nothing very elaborate needs to be done/built. But use your imagination!
In your everyday life, your generally insulated from the effects of Newton's third law because of the effects of friction.
Your assignment, therefore, is to devise some apparatus or setup which is able to both qualitatively and quantitatively (to some extent) show the existence of Newton's third law.
Hint: you need to come up with some device that is relatively frictionless.
Extra hint: Things on wheels are relatively frictionless.