The 'home room' is a nicely specific name for what I've just called a classroom, or formroom. In England, kids have their own specific formroom throughout - as Primary school pupils they stay in their most of the time, with their own form teacher; by the time they're 15 - 16 the formroom is mostly the place they go to first thing in the morning to have the register taken, and it's quite possible that their form teacher doesn't teach most of the students in that form.

In my Secondary school, our forms were actually named after our rooms. So, I:26 (ie One twenty-six) in my first year at Secondary, thereafter, II:25, III:31, IV:34, V:11. At my Brats' school, the forms were named after the teacher (using his/her initials), and by year number according to the 1 - 13 principle - 7JB, 8PA etc.

Thanks for the explanation - it is remarkable how different the system is.