At school I didn’t choose what I studied because it was a fixed program, but at high school I chose science. Once in science, I had a variety of options – maths was compulsory, but I chose physics, chemistry and biology to mention some.
We had to choose from ‘core’, ‘science’, and ‘all the rest’.
English and Maths were compulsory. I picked Biology and Physics, but Physics had to be replaced with Chemistry due to it clashing with my Computer Science choice (the school back then did timetables by hand… 😮 ), Art, and Geography.
Media and Electronics were dropped due to lack of interested students (my school wasn’t very big 🙁 )
A-Levels were Computer Science, Biology, and Maths.
If I knew what I’d be doing today back then, I would have kept Physics and tried to persuade the school to let me drop Geography for Computer Science. But again, it was good to keep my options open, and not restrict my opportunities which I would have if I started to specialise too early on.