For several years I've bought regular sized packs of Skittles for my students to do a "goodness of fit" test for a uniform distribution among the colors; that is, does the Skittles manufacturer distribute more Skittles of a particular color over others?
I buy packs of Skittles for each student, and have them count the total number in the pack, as well as the number of each color (red, orange, purple, green, yellow). (Incidentally, the experimental average over the years has been around 61 total Skittles in a pack, but recently the average is down to 60 (bigger Skittles?).) Students do chi-square tests for their own packs, and we also discuss the mean number for each color for all the packs together, and more!. I put all the data in R and display it on the overhead projector in a nice table (RStudio does this well).
But, you might ask, do bags of Skittles satisfy the requirements for the statistical tests you do? My answer: Um, well, but, Skittles are fun!
Nevertheless, I think this example has run its course for me. Years ago my students would get Skittles packs with anywhere from 40 something to 70 something Skittles, providing good examples for discussion. However, the last time I did the experiment we got the following for the total number of Skittles in 11 bags: 59, 59, 59, 61, 61, 61, 60, 60, 60, 60, 60. This variance is ridiculously low, the average was obvious, the confidence interval for the mean was obvious without computing, etc. I remember telling my students this is the most boring data set we've ever gotten for this experiment, and it's sad that I can memorize these numbers with so little effort.
There was still some interesting discussion, though, since there's always 20+ Skittles of one color when the expected number is around 12, when assuming a uniform distribution. And despite the usual variation among the colors, rarely is it ever statistically significantly different from a uniform distribution, which is always surprising to students. Also, this time we had a significantly low total number of yellow Skittles for the entire class.
OK, I changed my mind, I will probably continue this in the future.