But next time you face a difficult class, it might be worth asking yourself whether any of your pupils will have to go home to their own private hell, and to perhaps hold in mind that some of them certainly do.
When I first trained in child protection, I found myself enraged; too furious to be rational. I could not believe that adults were capable of perpetrating such horrendous crimes on small children. But they do. They beat, they frighten, they touch and prod their little bodies. They demean and belittle and damage fragile minds.
We know the huge amount of physical, emotional and psychological damage sexual abuse causes. We know the extent of child pornography, and the numbers accessing it. We know the huge amount of emotional and psychological damage sexual abuse causes. It is not unusual for police to find thousands of images on one computer. Yet every single photograph taken will have caused distress and despair.
We know the extent of the damage because of the adults who talk of their own childhood. Nowadays some teachers are aware enough to notice erratic behaviour, or bruises, and to listen and understand what a child is telling them. Except that children don't often speak out.
And it's not just the grubby, scruffy child who lives in the grottiest part of town. Look to the nicest, cleanest, smartest too - because abusive adults come from all walks of life. And some children desperately try to be good at school. It becomes the safest place to be. If you have been raped the night before, if you have been touched in a way that embarrasses and frightens you, if the worst thing ever has happened to you, why are you going to care what a teacher says about you not having a pen?
I am not saying that we shouldn't expect pupils to have a pen, or that we have lesser expectations for those children who face what they should never have to. But I am saying that maybe behind the horrendous classroom behaviour is a kid who very much needs a break, who needs to be welcomed into the sanctuary of your classroom, and who might well not feel the need to stand up to you as a teacher if they felt more valued by you as a person.
A baby girl has been damaged in her most tender and private of places. Can we just be aware that she is merely the tip of an iceberg and know that some of our pupils are hanging on for grim life?