Press the green flag. I highly recommend "Turbo Mode" (shift click the green flag). :-)
This project tests the random number generator in Scratch by plotting thousands of points on the stage. If Scratch's "random" implementation is sufficiently good, then we should expect to see a fairly uniform distribution of points on the stage. If not, then we will see clusters of points in certain areas. This technique for visualizing bias in a random distribution is called a "Matrix Diagram". You can learn more about this type of visualization in a great article by Mike Bostock entitled, "Visualizing Algorithms": https://bost.ocks.org/mike/algorithms
