The screaming filled the class and drifted down the corridor. Just as I thought it couldn’t get any worse, the performance gained an accompaniment of syncopated foot stamps and banging fists. And the performer showed no signs of tiring. It was Dexter, again - for the third time that week.

I’ve dealt with my fair share of behaviour issues, but this was a new one, both for me and my job-share partner. Having lulled us into a false sense of security at the start of term, he had erupted without warning.

One moment I was leading a class game of Who Wants to Be a Millionaire?, the next I was checking to see who had been shot as howls erupted from the corner of the room. Fifteen minutes later, Dexter was still in full screaming mode, all because he had lost the game.

“Do you want to rejoin, Dexter?” I asked. He fell silent immediately, as if someone had pressed a switch. “Yes, please.”

Once school was over, my partner and I discussed the outburst and drew up plans. Clearly sanctions were needed and we would have to talk to Dexter’s parents, but we hoped it was just a one-off.

It wasn’t. The next few weeks felt like teaching in a nightclub at kicking-out time. You could be midway through a calm and ordered lesson when Dexter would begin bawling. Playing maths games took on a dangerous new significance. The other children started to hold their breath when it was Dexter’s turn.

We weren’t about to be defeated by someone under 10, so we brought the full force of our combined behaviour management skills into play. An action plan was drawn up and signed by Dexter and his parents, sanctions were applied, a sticker chart was introduced to reward good behaviour.

But our best efforts had little effect. In fact, Dexter added furniture-kicking and object-flinging to the routine. The rest of the class, who had initially been scared, began to look on with bored expressions as they waited for him to wail it out.

We searched high and low to find the root of the problem but drew a blank: his parents assured us nothing had changed at home, Dexter said he wasn’t worried about anything, chats with past teachers revealed nothing more than a couple of tantrums and a tendency to sulk. The school’s social worker suggested autism; privately we thought it more likely to be an acute form of spoiled brat syndrome.

Then the outbursts suddenly stopped. Day after day, Dexter behaved like a model student. More than a week after his last outburst we were discussing an angry child in a guided reading book.

“He’s like you, Dexter,” Ryan said helpfully. “Do you remember when you used to scream and shout all the time?”

“Yes,” Dexter agreed amiably, adding, “I don’t do that any more.” We all nodded in agreement and carried on reading. I remain baffled.

Jo Brighouse is a primary school teacher in the Midlands