Disruption by naughty students is now routine, with almost nine in 10 (87 per cent) of school staff saying they have dealt with an unruly pupil this year.
In a survey by the Association of Teachers and Lecturers, almost four in 10 (38.6 per cent) teachers have encountered physical aggression in the classroom.
While most said this was towards another pupil, more than a quarter (25.9 per cent) said the violence was directed at them.
Nearly half (48.8 per cent) of teachers who had dealt with bad behaviour said they had faced students using their fists, while four in 10 (41.2 per cent) said they had seen pupils kicking.
More than one in five (23.7 per cent) had dealt with a child for spitting, the poll found.
And 1.4 per cent said they had dealt with incidents of a child stabbing or attempting to stab someone with a knife, pen or pencil.
A head of department in a Surrey state school told researchers: "In the past year I have been involved with incidents of smoking, drug abuse, assault, pupils 'losing it' and being out of control, very strong and repeated verbal abuse to staff and management, use of mobile phones in class, cyberbullying, etc.
"Such incidents are increasing and taking away teacher time from the main purpose of our jobs, i.e teaching."
The problems appear to be worse among younger children, with almost half of those questioned (48.3 per cent) reporting incidents of physical aggression in the classroom by a primary age pupil, compared to a fifth (19.8 per cent) in secondaries.
Almost six in 10 (59.2 per cent) of school staff believe pupil behaviour worsened in the last five years, and 46.1 per cent think it worsened in the last two years.
At ATL's annual conference, which begins in Manchester today, members will debate a motion calling for the union's executive committee to lobby the Government to give schools the means to deal with disruptive pupils.
It calls for parents of unruly students to have their child benefit cut, and for them to be forced to attend parenting classes.
A second motion calls for more priority to be given to behaviour in primary schools.
The vast majority of teachers (96.7 per cent) say bad behaviour interfered with classwork, ATL's poll found.
More than three quarters (77.7 per cent) said they experienced disrespectful behaviour such as pupils using mobiles in class and ignoring instructions.
Over half (51.6 per cent) said they seen pupils being insulting, swearing or threatening someone. A head of department at a Leicestershire state secondary school said: "I have been physically assaulted twice and sexually assaulted twice.
"I felt like going off sick but didn't – despite then being physically sick each morning at the thought of going to work."
More than a third of teachers (36.5 per cent) also say they have faced aggression from a child's parent or family member.
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