To think a teacher should not call a pupil an idiot!

[Namechangedbecauseiwantto]

Year 7, ds was messing with some magnet balls which he'd taken in without me knowing (he's not taking them into school again).
He got given a warning, and then second warning which means detention. I have no issue with this, he should do as he's told, but my issue is, he asked if he should take his stuff with him (at the end of the lesson when he'd been referred), the teacher replied "take your paper you idiot".
I have actually emailed the school to ask, and just been brushed off really. Aibu?

The example of the boy being slapped around the head is ridiculous, because whether it was twenty or a hundred years ago, it is not relevant nowadays

Also the vast majority of teachers 20 years ago wouldn't have slapped a student across the head. That one did and nothing happened to her.

I didn't say that it was okay for a teacher to call a child an idiot. I said your working day isn't comparable with a teacher's and I said that accepting that the child was called an idiot without first asking the teacher for their version isn't reasonable.