All of our AP science course are 1.4 credits - 1 period on 3 days and 2 consecutive periods on the other 2 days. One period, 3 days either goes to study hall or another interleaved AP science course. I don't think there are any other 2 or 3 day/week classes.

When I was in HS, AP Chem was last period each day, then Friday it was the last 2 periods, plus class until 4:30, so a 3 hour lab session. We have a late bus at school now, but no such thing in my day. My lacrosse coach wasn't a big fan of missing 80 minutes of practice every week.