Class dismissed

Class 507 is terrible, and one day, after a particularly disastrous science experiment, Ms. Bryce quits and walks out in the middle of class, and the school office never finds out--at first all the fifth graders enjoy goofing off, but after a few days that starts getting boring, and the students begin to realize that school without a teacher is not easy, cooperating is difficult, and keeping a secret is harder than they thought.