This isn't soccer-related, or soccermetrics-related, but it is math-related. I participated as a volunteer for the Arizona MATHCOUNTS competition this weekend. I've gone full-circle, because I competed in one of the regional competitions in Florida when I was a junior high school student in the late 80s. For those who don't know what it is, MATHCOUNTS is a mathematics competition for junior high school students, with local, regional, state, and national levels. There are individual and team competitions where students attempt to solve problems within a time limit, and then a "countdown" competition where the top individual competitors face off against each other by answering questions displayed on an overhead screen.
I would call it an applied mathematics competition; the questions cover geometry, algebra, probability, and combinatorics, which would be topics encountered by an advanced math student in junior high (okay, maybe not combinatorics). The level of the math isn't important. You can devise some very tricky questions using material from algebra and geometry. The American Mathematics Competitions, which are feeder competitions for the US team in the International Math Olympiad, are a mix of pure and applied mathematics using material from high school subjects. Those questions are insanely difficult, and I'm telling you that from personal experience.
My volunteer work was kind of boring – I was in the back room marking exam papers – but I later went to the auditorium to watch the countdown round. It is impressive to watch middle school kids solve tough math problems correctly in their heads and ring in before the moderator finishes reading the question. (I was doing the same thing, too, but I couldn't do that back when I was their age!)
So if you're interested in mathematics and would like to take a look at the next generation of math experts, I recommend volunteering for MATHCOUNTS. I especially recommend doing so if you competed while in school; it's a different experience from the other side, and just as rewarding.