Allan Woodrow is back with another pitch-perfect middle-grade novel full of hilarious antics, epic arguments, and a class that just doesn't get along. Class 507 is the worst class Ms. Bryce has ever taught. And she would know -- she's been teaching forever. They are so terrible that when a science experiment goes disastrously wrong (again), Ms. Bryce has had it and quits in the middle of the lesson. But through a mix-up, the school office never finds out. Which means ... Class 507 is teacher-free!