A survey of teachers suggests a rise in the number of pupils with emotional, behavioural and mental health issues.
Over half (56%) of the 844 teachers surveyed said behaviour in the classroom had deteriorated in the last five years. Sixty-two per cent said problematic behaviour was worse now than two years ago.
The survey was carried out by the Association of Teachers and Lecturers. A majority of those surveyed said they had been forced to deal with at least one challenging or disruptive pupil in the last year.
Over three-quarters (77%) reported verbal aggression, followed by physical aggression (57%). Two in five (41%) said they had experienced bullying in person, while just under a quarter (23%) reported students breaking or ruining the belongings of others.
Teachers reported being spat at, kicked, punched and scratched by pupils.
The survey found that 35% of teachers had not received any training to help them deal with challenging students, with 42% saying they did not get any relevant training on bad behaviour during their teacher training.
Nearly 80% of teachers felt the rise in bad classroom behaviour was down to a lack of boundaries being set by parents in the home.
Dr Mary Bousted, general secretary of ATL, said: "Regrettably teachers and support staff are suffering the backlash from deteriorating standards of behaviour.
"They are frequently on the receiving end of children's frustration and unhappiness, and have to deal with the fall-out from parents failing to set boundaries and family breakdowns.
"And the huge funding cuts to local services mean that schools often have to deal with children's problems without any help."