There is a maxim about expectation: we only achieve what we aim for. This dogma, which I first heard at a neuro-linguistic programming cult meeting, seemed the very distillation of prudence and sensibility. Since then, I have heard many teachers use it as a goad for the ambitions of children, and such aphorisms have become standard for the educator who seeks the best from their pupils.

It is sensible to have great expectations for children, whose ambition is often limited, cropped and crippled by the desperate, dismal autumn of their guardians’ subterranean horizons.

But why are the expectations of teachers so contradictory? While our expectations of children are supposed to be crystal clear, the demands placed on teachers are the incarnation of oxymoronism (with emphasis on the “moron”).

We are caught between two intercity trains pulling against each other on a piece of rope that has managed to work its way around my knackers. On one train, we have the expectation that pupils should learn, engage and blossom. On the other train is a different expectation - that teachers and schools should establish this fabulous learning life for children with as few behavioural management tools as possible.

I am talking about the trend that children should never be sanctioned against and that good behaviour should be sought by other means. When I started teaching, I was amazed that poor behaviour was seemingly tolerated by people who appeared to subscribe to the counter-experiential view that children should be chided softly for fear of demotivating them.

It is not laziness that inhibits many teachers, but ambiguity of purpose. This uncertainty often stems from their training - placement quality can be choppy. In other instances, it is caused by bad advice from tutors, many of whom are excellent, but some of whom are out of touch and have never handled a child shouting “fuck off”.

If teachers seem unsure of how to deter misbehaviour, some schools seem structured to encourage it. A low rate of exclusions became an indicator of quality for Ofsted, so - in the best traditions of playing the game - exclusions went down. I say “exclusions” rather than “expulsions” in case anyone mistook it for something nasty and had a coronary. Even the word exclusion has started to take on an ominous, negative tone: to exclude is a social evil these days. Some schools even have an inclusion manager.

But inclusion is not a goal in itself; it is a means to an end. It is not an intrinsic good. Do we “include” Harold Shipman or Attila the Hun? You can. I want them in jail or buried in an unmarked grave.

It takes only one or two really tough kids to ruin the education of a whole class for the entire span of their school career. Every teacher knows this. Such children, such extreme-spectrum children, need special provision, close supervision and more nurturing than they can receive in the mainstream environment. I am not advocating throwing them into an offshore Alcatraz - but give it time and we may end up with companies like RoboCop’s OCP running an academy chain near you.

In the meantime, the more social segments of the learning population can get on more or less civilly. I do not desire that any child should be punished. But it is necessary. And sanctions necessitate further consequences when they are flouted, or they melt away like mist.

You want social mobility? You want to see children reaching escape velocity from the cages of their demography and caste? Then we need an education system that acts like a grown-up and realises that, if we do not set boundaries for children, they will draw their own.

Teachers need a government that allows us to exclude without fear of recrimination or financial penalty. What this currently means for the majority of pupils are stints in learning bunkers or internal exclusion units, which disrupt other pupils and teachers. Some schools do a great job, but if the school has more than a small percentage of such children, then they cannot cope.

Ultimately, the education of the whole cohort gets stuffed for the sake of a few. The teachers’ working environment is shredded, along with their enjoyment of teaching. Plus, the education of the disrupter is often diluted to the point of worthlessness. So no one wins.

You want great education? I’ll give it to you. But let me do my job.