When I trained to teach, my first lesson was with a group of 14-year- olds in a temporary classroom stuck some way apart from the main school buildings. It symbolised to me, in my agitated pre-lesson state, visible detachment from the authority of the school.
The students were there before I arrived and I could see that several of them were fighting. I could hear jeering. I was walking knowingly into a lion's den.
The students were waiting to see what their new student teacher would be like. And I was struck by that gladiatorial sense of an arena - it was me against them.
The previous week, I had observed a veteran teacher with the same class and marvelled at the way he reined them in, creating a state of obedient silence without speaking a word. He just seemed to look at them and they became pliable. It made teaching seem somehow mystical. I could understand all those people who had told me that being a teacher was a talent you either had or didn't.
I had tried every trick in the book to give myself some superficial authority. I had grown some unconvincing facial hair and dressed in a middle-aged man's sports jacket and brown tie. Even in the mid-1980s I was an embodiment of 1973.
Quickly I learned, however, that teaching wasn't quite as mystical as I had thought. I realised that subject knowledge is less important than other stuff: knowing where to stand in a room, knowing how to signal that the territory now belongs to you (insisting that bags be on the floor rather than on desks, and so on).
In his collection of essays, What the Dog Saw, Malcolm Gladwell quotes an educational researcher, Jacob Kounin, who studies how teachers deal with low-level poor behaviour. The most effective are those who prevent the tiny misdemeanours - talking when the teacher is or losing attention - from growing into big misdemeanours.
The really interesting bit of Kounin's research is that this isn't really a matter of the teacher knowing how to deal with defiant or aggressive behaviour when it happens; it's about pre-empting the small stuff to stop it ever developing into bigger stuff. It's what Kounin calls "withitness".
I like that - "withitness". It makes sense to me. It's the way teachers make the classroom their own, model the behaviour they expect from students, use body language, pauses, praise. It's the real stuff of teaching.
That is why we need to keep the focus on teaching, rather than tinkering with the structural stuff. The more teachers are expected to implement a new curriculum - the "what" of the classroom - the less time they will spend on the "how". So let's avoid endlessly changing the curriculum. And to do that we will need our politicians to adopt a form of "withitness".
Geoff Barton is principal of King Edward VI School in Bury St Edmunds, England.