The child stars of the West End musical rock out in a band assembled by Dewey Finn, who poses as a supply teacher. What do their own teachers make of the hit show?What can teachers learn from Dewey Finn? It's all about organised chaos. One hundred years ago, a classroom was 30 desks with students sitting behind them and a chalkboard in front of them. Now, the majority of school life is exactly the same. I try to chan…