In the states, once you enter middle and high school, it is very similar to university. You have a different teacher for each subject, and you have to move around from classroom to classroom. At my previous high school, a normal day would look like:
8:00am 1st class -> 15 minute break -> 2nd&3rd class -> Lunch -> 4th class -> finish day at ~2:30pm
After school would usually be when club activities were held, or if you had any questions, you could usually go to the teachers for help.