I-85%The U.S. interstate system takes remarkably straight paths between major cities: specifically, I believe that the true distance between two cities is, on average, only 6/7 of the interstate driving distance. Here's a statistical activity I made for my students:
If they do a decent sample size, say n = 25, they will almost certainly reject the null hypothesis I state in the problem.
A Wikipedia theoryA tip of the hat to XKCD. The theory is simple: On any Wikipedia page, click on the first link that is not in italics or in parentheses; repeat; you'll eventually end up on the philosophy page.
My students tested this out (n = 160 trials). They found that they did always end up on the philosophy page, with a mean of 16 links required (and s = 4.6). Neat.
Researchers found that the number of link steps between two topics indicates how strong or weak the connection is.