Teachers believe they are failing some of the country's most vulnerable children - pupils with emotional and behavioural difficulties - because they do not have the time or resources to help them.
Today the National Association of Schoolmasters Union of Women Teachers will hear that the Government's policy of including children with behavioural problems in mainstream schools is a disaster for pupils and teachers.
A motion to the annual conference in Llandudno says the union is incensed at rising verbal and physical aggression in schools.
It urges ministers to reinstate fully-funded, relevant alternative schooling for pupils with behavioural difficulties and to increase the number of special schools and specialist off-site buildings for children with special needs.
Amanda Haehner, national executive member for south London, said: "The realities of inclusion are daily evident in schools. Pupils in need of specialist help are subjected to the rigours of the national curriculum and the inflexible testing regime. This allows our most vulnerable children to experience failure over and over again."
She said teachers were blamed by those who suggested that if only they made their lessons more interesting difficult pupils would stop screaming, swearing and hitting other pupils.
"Anger from teachers often comes from the feeling you are permanently failing the children in your care because you can't provide them with what they need."
Pat Lerew, union president, opened the conference with a warning that behaviour was worsening because today's parents were "Thatcher's children" who had grown up in the selfish 1980s.
Her daughter, Joy Windsor, who also teaches at Amery Hill secondary school in Alton, Hampshire, was due to call yesterday for a national system for registering violence against education employees and for teachers to agree a list of criteria for excluding pupils from lessons. Reasons could include racist behaviour, verbal abuse and "constant unreasonable disruption".
In an earlier debate, delegates demanded a change in the law to allow teachers falsely accused of physical or sexual abuse to claim compensation.
Charles Clarke, the Education Secretary, said that he was ready to look again at the issue of malicious allegations against teachers.
He told the conference: "This is a real issue and becoming increasingly real as people feel they can take a pop at authority."
However, Mr Clarke was sceptical about union demands for legislation to give teachers anonymity while under investigation.
The conference heard teachers lives were blighted by false accusations.
* a head accused by a teacher and trainee learning support assistant of assaulting a child who was cleared in court
* a "gentle" teacher accused of breaking the arm of a 6ft 2in Year 11 boy
* pupils bragging about getting teachers suspended.
Bids by the union's national executive to persuade delegates to drop the compensation call failed.
Bill Bradbury, a delegate from St Helens and Newton, said: "If it's good enough for the kids to claim compi, it should be good enough for us to claim compi."
Eamonn O'Kane, the union's general secretary, was unable to attend because of ill-health. Mr O'Kane, who won warm praise from Mr Clarke for his role in the workforce deal, sent a recorded message to delegates.