Two-thirds of the members of a teaching union have considered leaving the profession because of pupils' bad behaviour, a survey says.
Teachers say violence extends outside the classroom
The Association of Teachers and Lecturers' poll of 800 secondary school staff found almost all had experience of dealing with disruptive children.
Ex-teacher Phil Baker said he had confiscated knives and baseball bats.
Education Secretary Ruth Kelly promised to tackle bad behaviour inside and outside schools.
Mr Baker, who gave up teaching after being attacked by a parent, said: "I had to witness, during my 33 years of teaching, a whole range of incidents. "If you stand in a door sometimes the kids would just shunt you out the way. "I've had to disarm kids with baseball bats in their hand, in my last year I took three knives off pupils - a whole range of incidents which put you under great stress."
The ATL survey found more than a third of teachers had suffered stress or mental health problems.
Meanwhile, the NASUWT union, holding its annual conference in Birmingham, is demanding disruptive youngsters be taken out of school and sent to specialist units.
Figures have shown record compensation - £7.6m - was paid out last year for violence against staff.
General secretary Chris Keates said teachers had been abused by pupils outside school and besieged at home.
In some cases, children had posted pornographic pictures on the internet as part of a campaign against staff.
Ms Keates said: "In all of these circumstances the first defence of the parents has been, 'this has happened off-site, this is nothing to do with the school'."
Ms Kelly told the NASUWT conference that teachers would get clear rights to tackle violent and disruptive behaviour which occurs off-site, as well as on the school premises.
The Education Bill, going through Parliament, would challenge the "you can't tell me what to do" culture among pupils, she told delegates.
Parents must support the school to ensure their child's good behaviour, and had responsibilities as well as rights, she said.
Her comments were welcomed by Ms Keates, who said teachers were "worn down" by persistent challenges to authority.
"No more will legal advisers be able to argue that it is 'outside school and therefore none of your business'," she added.
Ms Keates said it was "contrary to the raising standards agenda to retain a pupil on site who needed off-site provision".