Afraid she'd lose her friends if the study group broke up, Annie sabotaged spanish class this week. She leaked to the dean that Senor Chang actually did NOT have a teaching certificate. This infuriated Jeff when the information leaked out, and he made sure people didn't feel sympathy for Annie.
But he and the group were faced with another problem: they must pass a difficult final, as prepared for them by a strict substitute teacher. By the end of the half hour, though, Pierce had taken care of this issue by (eewwww!) sleeping with the professor and ensuring an easy exam.
Everyone passed and everyone agreed to take anthropology together next semester. Annie got back into their good graces by helping Chang realize his dream of being a musician and helping him enroll as a student in Greendale.
There was also a subplot about Troy being a janitor and being recruited into that field, like Good Will Hunting but in reverse. Its concept was funny, but it fell flat as far as actual laughs went.