
Explore a Galton board, coin flips, dice and spinners in one place. Run a few trials or thousands, then compare observed results with theoretical probabilities.
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This simulation drops balls through a triangle of pegs. Each peg is a coin flip, so the bin a ball lands in equals its number of right bounces, a binomial distribution. Students set the rows from 4 to 14 and the bias towards the right from 0.2 to 0.8, press Drop 100 balls, empty the bins and show or hide the gold normal curve. Readouts give the balls in bins, the theoretical mean and the standard deviation. Teachers can use it to introduce probability, the binomial distribution and the central limit theorem.
Yes. It is completely free and runs in any modern web browser, including on interactive whiteboards, tablets, Chromebooks and phones. There is nothing to install and no sign-up or account is needed.
Each ball's final bin is the sum of many independent left or right bounces. Sums of many random choices follow a binomial pattern that looks like the normal curve, as the central limit theorem predicts.
For n rows and a chance p of bouncing right, the mean is n times p and the standard deviation is the square root of n times p times one minus p. The simulation shows both.
Choose rows and bias, press Drop 100 balls a few times, and compare the bars to the gold curve. Then change one setting and drop again.
Drop it into your LMS, blog, or class site — free.
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Explore a Galton board, coin flips, dice and spinners in one place. Run a few trials or thousands, then compare observed results with theoretical probabilities.
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