Most kids at about age 14 choose what subjects they are going to focus on for the next few years - I know when I was in school, I had to choose 8 subjects, I'm not sure how it works now (I left school in 1979). I did Math, English Language, English Literature, Physics, Chemistry, French, Geography and Religious Edication (!). From age 14 - 16, I focused on those subjects, and at age 16, took exams in them, which are now called GCSE's. (back then they were 'O Levels). Also, these days, the coursework they do during the year counts towards the final grade, I believe (in my day, it was all in the final exam). After 16, you can then go on and take 'A' Levels (another 2 years work) - I think the norm is 3 or 4 subjects, but some do more. You basically choose some of the subjects that you have already done in the previous 2 years, and expand on them - obviously, most people choose whatever will help them best in whatever they want to do when they go to University.
Parts of Harry Potter suddenly make more sense to me.
