In the US it goes Elementary k-5, Middle school 6-8, and high school is 9-12. College is a generic term for higher than that. Some areas they have a junior high instead of middle school where it is 6-9 and high school is only 3 years but not much anymore.
I went to college twice once to have a good time and once to get my actual degree. First time was amazing still have friends from those days but I barely went to classes. Now my second time at it I was on overage 14 years older than everyone else and I mean that is hard to get past but the school part was a lot easier this time. For the most part classes are easy if you go and pay attention. Sure some of my programming classes had me working 50+ hours a week on homework but I got through it.