Couldn’t put up with it.” It is hardly surprising. Any media mention of the profession these days seems to be a negative one - bullying, behaviour, belligerence. We can be seen sometimes as whiners in bad jackets with holidays that are too long, or, more often, as patient sufferers of incessant abuse.

If we secretly enjoy the status our apparent martyrdom brings, it is no surprise. We can often wallow in the seeming impossibility of the job.

Teaching reaches into the deepest corners of people’s lives and can be a considerable burden. It is not possible to be positive all the time, and when you are trying to hold children together as their lives crumble, we can be forgiven if we speak of the difficulties of the job before anything else. But if we can’t look at the majority of the children with whom we share our days and feel positive and want to work with them, we really should get out as quickly as we can.

There are times when we should pause and think. Is it that bad? If it is that awful, why do we still do it? We can’t all be trapped by our circumstances. It would be terrible if we were. It would certainly be shocking news for the children we teach. You see, I think there is an experience that keep us turning up every Monday - and that is the people who form our schools. In all their variety, all their diversity, they shape our days. They come to school and they bring their lives with them and that is why the days are as they become.

All these unique individuals come together and interact. That can never be quantified, rarely can it be anticipated. As a consequence, teaching demands special qualities. You have to think on your feet, adapting strategies almost by the minute, displaying cunning and sensitivity in equal measure.

It is this that gives the lie to those who believe schools can be compared; that in some way the performance of one school can be compared with the performance of another and supportable conclusions drawn. They cannot be, because a significant part of the process is forever unpredictable. People.

Unique individuals reacting uniquely; that is what Monday brings.

The influence of these indefinable, unpredictable things cannot be reduced to something scientific, something measurable, repeatable. I can teach the same topic in the same way to different classes to completely different effect. Sometimes a lesson will take off in unexpected ways and become a special experience. At other times, the same topic will burrow under a stone and disappear and, if the lesson were a horse, you’d shoot it. It is people who make that happen.

The interaction is so complex that I worry for those who believe the classroom is a simple and quantifiable place. I have observed enough lessons to know the most important resource in the classroom is the teacher. And I also know that the best teaching is often a carefully crafted performance. So how can anyone deny that performance can be determined by how that teacher is feeling, by what is happening in their lives? Broken cars, unexpected bills, disappointment, collapsing ceilings, collapsing marriages - the list is endless. All these events can and will influence the classroom experience.

Our pupils are the same. The child whose mother is in prison, the child who is abused, the child whose mother has a new partner, the child who can’t sleep because he shares a room and a bed with three others. All these factors make each class unique and contribute to its mood. The overspill from all our domestic lives floods in, for better and for worse. You can’t stop it. Put all of the above into a mixer and I defy anyone to predict what will come out. So don’t tell me that two lessons are ever, or ever can be, the same.

That is what enriches the day and, in many ways, that is what others envy about our job. A school is a community, like an extended family or a small village. It contains a warmth in its relationships, many of which endure far beyond the classroom years. We have an involvement with new generations, we can be involved in their development, we can influence them in positive ways, we can help build a future, perhaps a better one.

Does all this sound naive? It is not meant to. I teach in an underprivileged area and I know how hard the job can be and how much harder it is made. I can see how teachers are battered into submissive cynicism and I, like everyone else, sometimes stop and ask myself why do I still do it. I have bad days, when the criticism gets to me, when a lesson goes badly or when the irrelevance of the bureaucracy threatens to make me scream with frustration.

But schools are not only places of dissension and distress. I simply never know what is going to happen when Monday comes. I have to react to rapidly changing circumstances. I find myself dealing with issues for which no one could ever prepare. It is never simple; it is never boring. Of course it exhausts us, but what is it our retired colleagues miss? The people, all of them. Those of us still in work should make the most of it. You will never again meet a group of people like those in your own school.

Geoff Brookes is deputy head of Cefn Hengoed comprehensive, Swansea