# How big is the gulf of Mexico?

Term has now ended, undergraduate teaching has finished for 2012, and most of the undergraduates have gone home. As always at the end of term, there is a certain amount of relief, it has been 11 weeks of hard work. But also a bit of sadness. Campus is a quieter, duller place without most of the students, and I have enjoyed a lot of this term’s teaching.

Part of this was two tutorial groups of first years. They were at 3 and 4pm on Friday, so occasionally we all flagged a bit, I certainly did. The format of these tutorials is about 5 or so students and me, with a set of questions set by the teachers of the first-year modules (I don’t do those lectures, just the tutorials). A highlight for me was the question: Estimate the volume of water in the Gulf of Mexico.

This is part of a course that is aimed at helping the students learn how to make a rough estimate – a useful skill in physics where before either doing an experiment or making a more detailed calculation it is very useful to have a rough idea of what the result will be. Both my small group tutorial groups started out a bit reluctant to guess. I don’t know much about how A levels are taught, but maybe there is only a little estimating at A levels, so they are not used to it.

But in both groups, some had Googled it. This is resourceful, and gives the answer but was not really in the spirit of the question. But after a bit of a chat, we got the fact that Mexico runs along one side of it, and Mexico is very roughly 1000 km long, in the sense that it is a lot more than 100 km long, but a lot less than 10,000 km long. The Gulf is about square, so its area is about 1000 km × 1000 km = 1 million km². Then guessing a depth of around 1 km on average, you get 1 million km³ of water. Simple.

Both groups got it easily once I had suggested to them to think how big were the countries that border the Gulf of Mexico, and I think that they were a bit surprised how easy it was. Once they got going on the problem I enjoyed seeing the students work it out, and I think they enjoyed it too.