Teachers are being intimidated in their own homes by unruly pupils, a union has claimed.

One teacher returned from work to find the word “bitch” painted across her garden wall. Another found that his car had been scratched with a key. A third had 17 windows smashed at her home, while a fourth received a series of late-night obscene calls.

These events are just a snapshot of a much bigger picture of intimidation and damage to property endured by teachers daily, members of the Association of Teachers and Lecturers heard at their annual conference in Liverpool.

Even when they are on school premises, teachers cannot be sure that their property is safe. In the past year the union has received 146 claims about malicious damage to property and 69 claims of damage to vehicles.

Maxine Bradshaw, a teacher from North Wales, told the conference that pupils felt that they could get away with anything. “Parents and teachers feel powerless to discipline children for fear of repercussions or, worse still, prosecution,” she said.

Even when police did get involved with cases of vandalism, it was often a waste of time, she said.

When her car was damaged by pupils from another school she was offered restorative justice — in which perpetrators meet the victims to make amends. But the youngsters “appeared to feel no remorse” and offered an insincere apology, she said.

Ian Martin, from Bristol, said that he was aware of staff facing knife threats. On one occasion the knife had been made from copper in a workshop. In another incident a former student drove to a college and fired an airgun at pupils and staff, he said.

“A member of staff teaching 16 and 17-year-olds who had recently returned to work following a triple heart bypass was subjected to a student threatening to shoot him and students,” Mr Martin said.

Ms Bradshaw said that schools should follow the policy of many other public buildings with display notices indicating that they will operate a “zero tolerance” policy towards anyone who is violent or abusive to staff.

Although violence and abusive behaviour among pupils are commonplace in many schools, teachers are given very little training in how to respond.

Wendy Hardy, a teacher in Derby who works with excluded pupils and those at risk of exclusion, said that trainee teachers were offered just one hour and fifteen minutes’ training, during three or four years of study, on how to handle challenging behaviour.

A recent survey by the union found that challenging behaviour was one of the main reasons why one in five teachers leave the profession in the first five years of their careers.

But Irene Baker, a delegate from Sefton, Merseyside, said that schools were partly to blame. Pupils knew that they could get away with bad behaviour because the worst thing that they face is a talking-to. This would leave pupils little able to cope with the world once they left school and were forced to accept the consequences of their actions, she said.

Delegates warned of creeping state censorship over a clause in the guidance to the Apprenticeships, Skills, Children and Learning Bill that would give ministers the legal power to control the content of exams. Teresa Dawes, an English teacher from Berkshire, said that the move was “chilling and frightening”. Last year a group of MPs put pressure on Britain’s biggest exam board to remove a poem by Carol Ann Duffy, Education for Leisure, from the GCSE syllabus because it refers to knife crime.

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