Whats the name of this book?

When I was a freshman in high school we read this book in my government cl. It was about a teacher whose students ask him how all these people could follow Hitler during WW2. So he enacts an expirement where he starts introduving rules and slowly makes the kids into their own facist regime within the school. And in teh end he exposes their great leader, gatherst hem in the gym and shows them a picture of Adolf Hitler and explains to them what he did.