But have you ever noticed how some primary teachers start to behave like the children they teach? Think of those reception class teachers who roll on the carpet and sing "Incey wincey spider" just like five-year-olds, and then, once in the staffroom, spill coffee and biscuit crumbs down their front at break time, only to be told off by the deputy head for making a mess. It can happen to any of us.
I remember standing in a queue for a meal at a conference of primary teachers. One teacher at the back, feeling no doubt as peckish as Year 6 at the end of a long morning, jokingly gave a bit of a push, rather like Darren Rowbottom would have done, and several teachers tumbled into each other. "Now somebody's being silly," another teacher remarked disapprovingly. Two house points lost.
Perhaps it is the effect of spending hours having to deal with certain difficult pupils and then having a golden opportunity to misbehave yourself. Teachers driven to distraction by pupils refusing to do as they are told must love getting stroppy with the head and seeing somebody else on the receiving end of perversity.
There is a psychiatric condition known as folie a deux. It occurs when someone who is sane lives with someone who is mad. The sane person starts to appear mad and imitates the behaviour of the person who is insane.
One teacher had to cope with a wild seven-year-old who was quite likely to run out of the school several times a day. The school was next to a busy bus route. The only way she got through assembly was if another teacher held him down while she bawled "All things bright and beautiful" in his left ear, in the faint hope that he might join in. She confessed that, on her way home at the end of the day, she felt an almost irresistible urge to tip off policemen's helmets and run away.
I once taught a class of children that had quite a number of slower learning pupils. One of them, Wayne, always replied, "I do ant know" in his delightful regional accent every time he was asked a question. In desperation I asked him one day who Margaret Thatcher was, after she had been on television every second of the previous night. "I doant know 'oo Margaret Thatcher is", was the endearing reply.
After a few weeks of this unfailing repetition, I found myself saying, in perfect mimicry of Wayne's plaintive voice, "I doant know" to any question to which I did not have an answer.
One school in our locality found it had a problem with a term of abuse commonly used in the area. If any child appeared not to catch on immediately to a piece of classroom or playground conversation, other pupils would tap their forehead, put on a gormless expression and call out the word "Digby", the name of the local mental hospital.
Patiently the head and staff explained, cajoled, coerced. It was unkind to mock anyone, they pointed out. Moreover, the people in Digby were not lunatics or retards, many were simply frail and nervous, needing shelter from the hurly burly of everyday life.
Gradually the pupils stopped calling out "Digby" and the term faded out of use. Everywhere, that is, except in the staffroom, where head and teachers alike cheerfully tapped their foreheads, put on a gormless expression and called out "Digby" every time one of their colleagues failed in attention.