State schools "could go down the tube" without action on classroom indiscipline, the National Association of Schoolmasters Union of Women Teachers heard last week.
Ian Clydesdale, the union's Scottish president, told its annual conference in Carnoustie that it was time for the Scottish Executive, local authorities and headteachers to take tough action against abusive pupils.
A small number of pupils in each school were causing repeated difficulties for teachers who had no effective sanctions.
"There are many, many teachers out there who think it is their fault when classroom discipline breaks down. And worse still, too many employers and parents who think it must be poor teaching that is to blame," Mr Clydesdale told delegates.
"What crass nonsense. Let those who believe that spend a week in a classroom of disaffected S3 boys."
Rhona Mackenzie, of the union's recruitment team, said: "No one here is denying that we have a large number of emotionally fragile children who need a great deal of help and support. But who in their right mind would consider that the best place for these children is in a mainstream classroom with an already overworked teacher?"
She favoured removing troublemakers to a special unit or offsite facility, depending on the magnitude of the incident and previous behaviour. These should be staffed by appropriate agencies which have the training and time to deal with such children.
Mike Corbett, another recruitment team spokesman, said that senior managers were under pressure to keep pupils in school because of pressure from local authorities and above them from the Executive.
Authorities were legally obliged to provide education of a similar standard to pupils who were excluded for 10 days or more. That was why heads did not exclude. "Local authorities do not have the resources to provide behaviour management centres and one-to-one education," Mr Corbett said.
Joe Foy, South Lanarkshire, said that every school in the country had pupils "wandering around the corridors, hiding in the toilets, sitting outside the headteacher's room and usually the first pupils visitors see.
"We allow pupils to disrupt the education of others, not for an hour or day or a week or term but for years and it has to stop," Mr Foy said.
"Parents have a right to expect that their children's education is not disrupted by others. They also have a duty to ensure their child is not disrupting the education of every other pupil in the class."
Ann Attridge, Highland, said that in Portree most of 50 new housing association homes had gone to families from London and the Midlands who arrived with different standards of behaviour.
LITANY OF COMPLAINTS
* "Violent pupils do as they like, are suspended for three or four days and then return to intimidate the rest of the school. One took his belt off and used it on another pupil's face. An ambulance was called, the pupil was given an oxygen mask, blood was spattered over the depute head who went to the victim's aid and the victim was kept in hospital for 24 hours. The attackers are back in schools. How bad does it have to get before they are expelled? What message are we giving out?"
* "Death threat to a teacher . . . got the pupil lunchtime detention!"
* "There is no 'ultimate' threat between staying in (which most children don't mind) and exclusion which is too extreme for most incidents. This results in punishments which don't fit the crime."
Survey of Scottish members