[Feature photo above by Tobias Wolter (CC-BY-SA-3.0) via Wikimedia Commons.]
Seven years ago, our homeschool co-op held an end-of-semester assembly. Each class was supposed to demonstrate something they had learned. I threatened to hand out a ten question pop quiz on integer arithmetic, but instead my pre-algebra students voted to perform a skit.
I hope you enjoy this “Throw-back Thursday” blast from the Let’s Play Math! blog archives:
If seven people meet at a party, and each person shakes the hand of everyone else exactly once, how many handshakes are there in all?
In general, if n people meet and shake hands all around, how many handshakes will there be?
7 friends (non-speaking parts, adjust to fit your group)
Each friend will need a sheet of paper with a number written on it big and bold enough to be read by the audience. The numbers needed are 0, 1, 2, 3, … up to one less than the number of friends. Each friend keeps his paper in a pocket until needed.