A teachers' leader has said footballers like Manchester United's Wayne Rooney set a bad example to children.
Rooney was caught swearing at a referee by TV cameras
Rooney was caught on camera swearing at the referee more than 20 times, in an outburst during a game at Arsenal.
Hilary Bills, president of the National Union of Teachers, said this gave children the impression swearing was acceptable.
She was speaking ahead of a debate at the union's annual conference on deteriorating pupil behaviour.
Cheating and violence
Delegates say poor behaviour is a key concern, putting people off teaching.
Mrs Bills, a primary school head teacher, said anyone swearing in her school was suspended for a day.
But she said older children tended to copy what they saw their football idols doing.
"They ape what happens on the football pitch," she said.
"I'm sorry, when Wayne Rooney walked across that football pitch and swore, the message went out there that that's acceptable."
She is not the first senior teaching figure to criticise the game.
Earlier this month, Martin Ward, deputy leader of the Secondary Heads Association, said football was such a bad influence that it should be shown only after the 9pm watershed.
Verbal abuse, cheating and violence among players were commonplace, he said.
Football authorities say they have tightened the rules since Rooney's outburst and any player who behaves in that way again will be sent off.
On Sunday, Football Association spokesman David Davies told the BBC the FA may consider calling managers and players in to advise them of their behaviour.
The NUT conference is expected to say many factors can contribute to poor behaviour.
These include social deprivation, fractured families, the media, and the pressures of the curriculum and testing.
A resolution to be debated on Sunday calls on all political parties to tackle the issue.
One proposal is for all the teacher unions to draw up "a charter of minimum acceptable behaviour" expected of all students.
Another refers to "persistent low level disruptive behaviour".
In recent weeks the English inspectorate, Ofsted, has drawn attention to this as a growing problem - with politicians saying tackling this is a priority.
The government said it wanted a "zero tolerance" approach.
The Tories intend to let head teachers exclude disruptive pupils without appeal, while the Lib Dems say a better curriculum is the key.
But another complaint from the NUT is that exclusions can trigger inspections by Ofsted and the Welsh inspectorate, Estyn.
NUT members are also unhappy about what they call "the serious and growing problem" of abusive parents.
The union's leaders are also drawing attention to the need for local authorities to provide a range of alternatives for pupils with behavioural difficulties and other special educational needs.