I was in the staffroom, bemoaning an unproductive lesson in which the pupils had been impossible to discipline, when a more experienced colleague pointed out that it was a windy day. Why should this matter?

She explained the adverse effects that any change in the weather has on children. Wind is apparently one of the worst as it seems to make them whirl round like the leaves (and litter) in the playground, making a quiet afternoon a ridiculous notion. But rain causes bizarre and unpredictable behaviour. And as for snow, well, I imagine you may as well not plan any lessons at all. Not because you’ll insist that you’re snowed in and can’t possibly get out of bed, or that the kids will have the same idea, but because every single snowflake that flutters past the window will cause gasps and hysteria. Every member of the class will need to run over to inspect the situation.

Then there’s the soggy clothing and puddles that form under coats and wet shoes, which can only add to the confusion and riotous atmosphere. I was even warned before my teaching practice that it’s not just changes in the weather that can explain changes in behaviour; the phase of the moon is another contender. Perhaps there’s a scientific reason for this, such as pressure changes? So why don’t teachers get the same buzz from it? Even if I can accept weather as a valid excuse for writing off a lesson, I find it hard to credit some of the other excuses we come up with to explain behaviour.

There are the usual ones - Friday afternoon; nearly lunchtime; just after lunchtime - on which we all concur, but I’ve heard some other pretty unlikel theories.

One Friday afternoon I was told that my class was not only suffering from Friday-itis, but had also just been given their option booklets in registration. It seems the prospect of choosing their GCSE subjects had provoked major mood swings. My lesson was not running anywhere except out of my hands.

But it’s changes in routine that really do it. The predictability of the timetable means that before the day even starts the pupils know when lunch will be, when lessons start (whether they choose to be on time or not), when the day finishes, when the school bus arrives. As a result, even the slightest change sends tremors of unrest, change, even rebellion, through their ranks.

Meningitis jab day was a great example. It should have been declared a national holiday since, whether you were teaching before or after a class was jabbed, there was some reason for disruption. Whether it was the fear or coping with the aftermath of nausea, tears, and spots of blood on white shirts, children weren’t interested in literature, algebra or any other “er”.

But the pay-off came the following day when a certain calm pervaded the school. The children were quieter, less boisterous, more docile.

perhaps some of these excuses for disruption aren’t so bad after all. I felt this acutely when I complained of a headache on the way home, and was reassured by a PGCE colleague that it was probably the change in weather. I was happy to accept the excuse this time, but it’s funny how it didn’t send me tearing down the corridors and bouncing across the classroom; just into a hazy doze.

Katharine Lee is a PGCE student at Oxford university