The National Association of Schoolmasters Union of Women Teachers published figures showing that serious attacks on teachers are up by 37 per cent on last year.
Many attacks are by pupils who have been excluded from school by headteachers for violence and who are returned after appealing, says the survey.
One Sheffield pupil who had been permanently excluded for threatening a teacher with a knife was reinstated by governors. In a Birmingham school teachers and pupils were regularly attacked by a five-year-old.
There were 51 violent incidents, mainly attacks on teachers, compared with 37 last year, says the NASUWT. The previous highest figure was 50 assaults in 1987.
The figures include only the most serious cases in which the union has been asked to intervene. Most incidents are dealt with by individual schools.
Nigel de Gruchy, the union's general secretary, said: "These figures are only the tip of a very large iceberg of indiscipline.
"The worst aspect is the number of children who have been returned to their schools on appeal after being excluded by school heads and governors. It is time for teachers to be supported in their efforts to teach the majority of children who want to learn without fear of violent disruption."
This year's attacks include: regular attacks on teachers and other pupils by a five-year-old in Birmingham; in Wigan, police had to be called to remove a pupil who assaulted a teacher; a primary pupil returned to school after exclusion after attacking pupil with scissors; in Wolverhampton, three pupils and parents violently attacked teachers; and a violent junior school pupil in Kirkless was allowed to return to school by a headmaster who did not believe in permanent exclusions.
t A school troubled by youths threatening violence against pupils is to seek an injunction today to keep them off school premises.
Even as the legal action was being prepared, two youths burst into a classroom at Bretton Woods Community School, Peterborough, Cambs, and assaulted a 14-year-old boy in the middle of a GCSE English class.
The incident on Monday - and today's hearing at Cambridge County Court - highlight the level of violence plaguing Britain's schools.
The head at Bretton Woods school, John Gribble, said all schools in Peterborough were "from time to time" targeted by trouble-making youths.
A pupil had been threatened by youths on school grounds three weeks ago, Mr Gribble said.
That incident was not sufficiently serious to warrant police action and officers had advised that the school take a civil action.
"In the case of certain named individuals, they said that if we could get a court order preventing them from entering the grounds, they could be arrested if they did so," said Mr Gribble.