A supply teacher who wrote swear words on the blackboard and showed pupils a photograph of a naked man has been banned from teaching for at least five years.
Stephen Holmes, from Douglas, Isle of Man, discussed oral sex, his wife's vagina and asked children to guess how many times he had had sex in the past year, a disciplinary committee heard.
England's General Teaching Council were told how he swore in class and encouraged pupils to do the same during a maths lesson.
The panel, sitting in Birmingham this week, found Holmes guilty of unacceptable professional conduct after hearing how he had committed the offences on February 10, 2005 at Albany science college, Chorley, Lancashire.
Holmes, who was not present or represented at the hearing, had been employed through an agency, but was sacked by the school after just one day.
Margot Hall, for whom he had been covering, returned to be told by her pupils what had happened.
In a statement, she said: "Some of the pupils were completely appalled.
During the lesson he swore using the f-word and had written the c-word on the board before rubbing it out quickly."
Paul Crowther, then head of Year 8, said he investigated the claim after receiving a complaint from a parent: "The parent was concerned that during the lesson Holmes had acted inappropriately and used sexual language.
"Because it was literacy week, he had chosen the word 'obscene' as a focus of his lesson, despite the fact he was teaching maths.
"I spoke to the English teacher who took the lesson after and she said the pupils couldn't wait to tell her what had happened."
Andrew Faux, presenting officer, said: "It was a bizarre way to teach as a supply teacher."
Barry Carpenter, chair of the committee, said: "His actions seriously undermined and demeaned the pupils. He also failed to take reasonable care in relation to their emotional well-being. He has brought the teaching profession into disrepute."