^ This is why I think they could push it to a fourth season. If they wanted to...they could do a one year after Community college type season where we follow where everyone has gone. That could be interesting.
I added an edit in which I mentioned that each season appears to correspond with a semester rather than a school year. That would mean 4 school years would equal 8 seasons. Though, it sounds like Jeff might need an extra semester or two to graduate. I could see the registration system forcing everybody to stay in school for 9 or 10 semesters (meaning 9 or 10 seasons).