Schools' disciplinary codes are often lax and need reviewing, they say.
More than 500 members - mostly in the secondary sector - responded to a survey on levels of violence and disruption and almost 80 per cent say that they are still expcted to teach pupils who disrupt lessons.
Some 27 per cent had been physically assaulted and 91 per cent of incidents were reported - 16 per cent to the police. Charges were brought against pupils in fewer than half (43 per cent) of these cases. Schools excluded pupils who assaulted staff in 54 per cent of cases and suspended them in 31 per cent.
More than seven out of 10 of the union's members say they have been verbally threatened and abused by pupils.