School is surprisingly educational. That won’t come as a bolt from the blue to teachers, but for parents, it’s a rare and wonderful thing. For me, “educational” has been one of those weasel words, like “natural” or “organic”, that manufacturers slap on to their products to persuade idiots like me to buy them for the good of my little darlings.

I have bought educational toys (every toy for the under-fives is an educational toy, apparently), educational clothing (buttons and zips are educational, you see), and educational CDs of Mozart sonatas sung by whales to be played to the foetus in the womb (exceptionally educational, there is no doubt). Adulthood is not immune from this urge for bogus self-improvement. I wonder how many hours I have spent watching episodes of Call My Bluff, on the pretext that I might learn something. And yet, I bet it hasn’t added a single item to my vocabulary. You try your best, but the mind starts to wander. Even as a child, Robert Robinson’s comb-over could do that to you. The Nineties revival with Bob Holness set my mind racing, but only to ask what was I doing with my life if I had time to watch a light-hearted panel game five mornings a week?

Anyway, in school, I learn new stuff all the time. And so do the children.

Today, we learn about chunking. And what is chunking, exactly?

Well, Robert, chunking is a 19th-century style of Oriental porcelain, noticeable for its especially translucent quality and the fineness of its finish. The name comes from the Anglicised corruption of the ancient Mandarin, Xianxin. For the burgeoning urban middle-classes, a Chunking tea set was the height of Victorian sophistication.

No, no. That’s not it. Chunking is the term in Australian Rules football that refers to two players simultaneously tackling the same opponent. The game’s authorities banned the practice, but had to reinstate it at the insistence of TV executives.

I’m sorry, you’re both wrong. Chunking is a method of mental arithmetic, where you break the difference between two numbers down into several component parts and then add those parts together. It is one of several methods of addition which children are taught so they can pick the most appropriate for their own style of learning.

Chunking, unlike smart yoghurts or mental trousers, is very obviously educational. At the beginning of the lesson, the children can’t add together such big numbers. By the end, they can. (Well, most of them can. I reckon the boy I was helping went home thinking Chunking was ancient Chinese porcelain.) Michael Cook is a freelance writer and parent-helper at Jesse Gray primary school, West Bridgford, Nottingham, which his children Alfie and Poppy attend