[hdctambien]

At my school students have four 1.5 hour classes a day. Juniors and Seniors can have 1 of those periods be an "off period" which they can use as a study hall or they can just leave campus.

Plus lunch and 8 minutes between classes.

The school day is from 9 - 4.

This is very different from the school I taught at in Massachusetts which starts before 7am and has seven 45 min classes (plus lunch).

It really all depends on your district. It seems many commenters here believe that all schools work the same way their school works, but they are actually remarkably different across the country.