Paul Gronke writes,

I conducted the 100 pieces of candy demonstration and it did not work! Why?

I made one error that made it possible. Rather than using 80 pieces of small candy and 20 large, I allowed some “medium” (Halloween sized) candy bars.

But the real problem was this: one of the students was vegan and did not want to win. So she purposely chose five of the life savers in order do a “bad” job.
She ended up underestimating and getting closest … thus winning the candy!!

P.S. The candy demo is described in Section 3 of this paper (and also in my book with Deb Nolan). I met Paul at this workshop on teaching statistics to political science students. One thing I remember about this workshop is that the participants, who taught political science at small colleges, seemed to have about 4 kids each.