Rabid Dogs

Teaching a difficult class is like looking after a rapid murderous dog.

You cannot stop it being rabid and murderous, but you can be sensible about how you look after it.

If you don't have a plan to keep it contained or occupied, things will go badly. If you forget your past experiences and fool yourself into thinking it can control itself and rise above its situation, things will go badly.

Things will occasionally go badly. And you start to feel that its somehow your fault the dog is rapid and murderous.

It isn't your fault.  But you've got to stop thinking you can fix the dog, and accept that all you can do is contain it, and work on that.