# A mathematician watches the World Cup

This summer, I am focused on three things: math, travel (for math and for family), and the World Cup. Not surprisingly, many others are focusing on the World Cup and there are lots of blog posts and articles about World Cup related things. In this post, I wanted to draw attention to all of the math AND World Cup related things that have caught my attention. So here is a list of facts, articles, and blogs, in no particular order.

1. Did you know that one of the refs is a former high school math teacher? According to Wikipedia, Mark Geiger, who has been praised as a very fair referee (until perhaps a call earlier today during the Nigeria-France match, in which he may have been a little soft), “became a United States Soccer Federation National Referee in 2003 and has been officiating in Major League Soccer since 2004.” Once I heard this, it seemed like such a reasonable transition! As a high school teacher, you learn to manage a bunch of hormonal young people who mostly dislike you and all of your rules, which seems to me to be the hardest part of being a referee. Well, that and catching every foul and knowing how to sanction them, which I am pretty sure I would be terrible at. And you have to run a lot. I would rather be a high school teacher, I guess, except Geiger probably gets a much better salary.
2. There was a very fun article on BBC News recently about the birthday problem (which is also known as the birthday paradox) in the context of the World Cup. This problem is one of my favorite things to teach when I tell my students about probability, and now we have a fun, current-events related version! I don’t want to spoil it, but in essence what you would expect from the birthday problem is represented in the World Cup teams, so that’s pretty nice.
3. Fivethirtyeight has been doing some great World Cup coverage. They have crib notes for every day’s matches predicting the results, and more general predictions about the whole tournament (where you can also read about how they came up with their prediction model). They also made predictions for the group round (now over) and they were actually pretty good, as you can read about here. But as we all know, soccer (or futbol) is a pretty unpredictable game, so don’t despair, not-Brazil fans, there is hope for your team yet (as long as it hasn’t already been knocked out).