This blog on Central limit theorem animation by Nathan Yau brought back fond memories of a quincunx (better known as a bean machine) that I built to show operators how results can vary simply by chance. It was comprised of push-pins laid out in the form of Pascal’s triangle on to a board overlaid with clear acrylic. I’d pour in several hundred copper-coated BB’s through a funnel and they would fall into the bins at the bottom in the form of a nearly normal curve.
Follow the link above to a virtual quincunx that you can experiment on by changing the number of bins. To see how varying ball diameters affect the results, check out this surprising video posted by David Bulger, Senior Lecturer, Department of Statistics, Macquarie University, Sydney, Australia.