Our kitchen looks showroom-good for about 10 seconds a year; generally when we're out. It was during one of these brief nano-moments over the school holidays, when I said to my 12-year-old son, in full expectation of a breezy negative, ‘So, tell me, Archie, have you any holiday homework to do?'

‘No,' he said, with a Julia Roberts' smile. ‘Well, apart from making a castle.'

My world spun. The Parthenon nearly killed us in Year 3.

‘What do you mean ‘A Castle'?' I said heavily.

The dread piece of paper was unscrambled from his bag: a holding cell for squalor on an unparalleled scale. A rag it was, the instruction sheet, more crease than intrinsic whole, but horribly busy with required detail. For it was not just any castle, vague on accuracy, but a Norman one with a list like a fusspot at an estate agent, with demands for motte and bailey (the terms just trip now), drawbridge, palisade and dwellings, stables and outlying lands. The latter, you will note, being firmly in the plural. Please imagine how the maternal heart sank.

We looked it up. The website said, ‘The advantage of motte and bailey design was that it was quick and easy'. Yeah, right. Indeed, ‘Some only took two weeks to construct'. Fab. We had two weeks, perfect for wrecking with holiday homework.

Why do schools do it? Cast such a blight on necessary dossing time? Why? And this was for history, not art; could not a hastily scrawled paragraph suffice? My son's peer group is drawn from over 60 primary schools. These kids take buses, they travel miles laden down with school books, sports kit, aprons for tech, apples for tech (don't ask, it's a knife thing) and now a bloody castle with motte and bailey and outlying areas.

But before the putative horror of conveying it, came the practical horror of constructing it. ‘Despite being simply made' was the one phrase to give me hope. Fool that I am to rely on hope. I've been let down before.

I set to it with avidity, taking my duty rather more seriously than Archie who was sucked away by the greater importance of downloading Akon to his mobile phone.

Meanwhile I texted my chum and fellow Year 7 mother Mrs Northern Posh (who was sunning herself at her European pad), eager to wipe the smile from her face. She assured me the sun was shining and that, ‘how little you know me. Castle in hand.' Back in Blighty, I shook a fist at the rain-heavy sky.

The kitchen was soon in tatters and it was proved quite quickly that castles on this scale are not made quickly, nor are they easy. Furthermore, they require expensive forays to the supermarket to buy cheap flour and salt and, ok, wine and ‘Now That's What I Call Music 849' which Archie assured me would ‘help' while away the hours. Well, the wine helped.

Lurching from craft to craft, from crap salt dough buildings which rocked and sulked and resembled not a jot actual buildings, to rubbish papier mâché (the economics of making our own paste causing just the one ruined saucepan and a nasty burn on my wrist. I understood what the website meant with its: ‘The Middle Ages encompass one of the most violent periods in English History and are epitomised by the castles'. Yes, yes, yes) and finishing, messily, with glue and fabric.

Some seeming decades later, the new motte and bailey expert drove the wretched thing into school: the bus would kill it. As it was, the castle wobbled in the wind as I tottered across the car park. The website had suggested that ‘they were of great temporary value'. I'd question ‘great.' Or ‘value' actually, although ‘temporary' was going to be on the money. The history teacher was gratifyingly impressed to see it (although I'm not a great judge of reaction), and I was certainly more than grateful to see the back of it.

Back home, relieved and almost cheery, I spotted Nat (aged 10) lurking, swinging against the larder doors. ‘What's up?' I asked.

‘Nuffin,' he said automatically. Then, ‘We've got to make biscuits. For school. It's a project we're doing on Australia. We also have to make a landmark.'

Palpitations set in around my heart. Veins and arteries and things contracted. ‘A landmark?'

‘Yes,' he said, ‘the Sydney Opera House. I'll need a balloon. And I want my biscuits to be like mountains.'

‘Biscuits aren't like mountains,' I said bravely.

‘These ones will be,' he said, ‘And with a shed. And a goat.'

I can't wait.