The BBC has been criticised for an episode of Lily Allen's chat show after the singer showed a clip of a pupil pulling a teacher's pants down.
The BBC3 programme Lily Allen And Friends showed the footage on Tuesday night.
Pop star Lily Allen told the audience: "Now it's my favourite, it's kegging - pulling someone's trousers down in public when they least expect it. It's very childish, but very funny."
But the teacher's union has condemned the decision to broadcast the clip.
"It was completely and utterly irresponsible," National Teachers Union executive Andy Brown said.
"Broadcasting like that should not be allowed.
"The BBC is a big enough organisation to understand given the media furore over this kind of thing.
"It would be somewhat euphemistic to suggest it is naivety."
Of Lily Allen, he said: "If she doesn't understand the responsibility of what she is doing in the media world, then she should not be allowed to do that."