Parents are to blame for the increasing levels of disruption in classrooms, say education experts and teachers' union leaders.
At a cross-party hearing on behaviour in schools, MPs were told that low level disruption, such as pupils refusing to stop talking or sit down, was rife because children copy the behaviour they see at home.
The effect of this, they claim, is to undermine teachers' attempts to instil discipline in the classroom.
David Moore, an education consultant and former senior Ofsted inspector, told the hearing: 'Adults have to model behaviour they want, otherwise how does the child learn?'
'Children come from homes where they see a variety of types of parenting and they bring these models with them.'
'If you go into any shopping centre on a Saturday and you watch parents interacting with their youngsters you can see why the youngsters behave the way they do, because they model the behaviour of the adults.'
On average, every teacher loses 30 minutes of teaching time a day because of low level disruption, said Dr Patrick Roach, deputy general secretary of the National Association of Schoolmasters Union of Women Teachers.
Four-fifths of teachers believed the behaviour was more challenging than five years ago, he added.
Christine Blower, general secretary of the National Union of Teachers, said there had to be a 'common understanding' between parents and teachers over acceptable behaviour.
'The classic thing is that a child hits another child in the playground, and the child who has been hit goes home and the parent says: 'Well, hit him back next time. And of course, that will not be, for the most part, the discipline and behaviour policy that operates in school.
'There are very basic misunderstandings or differences of values,' she added.