It's lunch-time and there's a knock on the door. A small child enters and asks tearfully whether her plastic finger-mouse has been handed in. When I can't produce it, her disappointment is obvious. It might have come from a cereal packet but to her it's clearly no mere knick-knack.
I wish people were as conscientious about clothing. I can guarantee that by the end of every term the large, green dustbin which is kept in the office will be jammed with lost property. The smell is dreadful, which is probably why the cognoscenti avoid it. They prefer to write off their losses.
Parents find the strangest places to put their mark and we simply don't have time to search every hem, cuff and collar. Every year I emphasise to new parents the importance of naming garments clearly, including shoes, and that re-naming will be necessary. I tell them about the dustbin and I'm confident that they've cottoned on, so to speak. But it's a waste of breath.
We all know how easily one child can don another's sweatshirt - less so shoes or pants, but it happens - and although unpleasant weather should remind them if anything is missing, I wouldn't bet on it. A colleague once received an angry letter from a mum complaining that her dearest had been sent out to play in the cold. "It's all right for you," she wrote, "standing there raped in your fur coat."
Then there are sandwich-boxes. They're seldom all collected at the end of the day and they always include leftovers. Just imagine the mould after a holiday. Some parents puzzle me. They may forget exactly how many layers of clothing their offspring started out with, but surely they know whether they've made sandwiches or not.
It's the sheer value of the abandoned property, not only the volume, that beggars belief - piles of the stuff worth hundreds of pounds, some of it easily recognisable. But herein, perhaps, lies the crux. The fact that it's valuable doesn't necessarily mean it is valued. Cardigans and ties are clearly not plastic finger-mice.
* Luke Darlington is headteacher of St Mary's C of E primary school, Yate, Bristol