A Quincunx is a triangular array of pegs. Balls are dropped onto the top peg and then bounce their way down to the bottom where they are collected in little bins. Each time a ball hits one of the pegs, it bounces either left or right.
If there is an equal chance of bouncing left or right, then the pegs collecting in the bins form the classic “bell-shaped” curve of the normal distribution.
The Quincunx Explained page shows how this resource can be used to introduce the binomial distribution.
15 September 2012 Edit: 9 May 2022