"What's changed in the last 10 years is the level of violence with girls. In some cases, girls have become more physical."
In the past, it was more non-violent disagreements or bullying among female students, which was mainly verbal.
However, violence on the whole was decreasing, Mr Harray said. This had a lot to do with cases such as the death of a 15-year-old West Auckland schoolboy, who was fatally injured after rugby training last month.
"That really hit home. That's something that our students have thought really long and hard about."
Education and taking anti-social behaviour seriously were the best ways to avoid violence at school, he said.
Mount Maunganui College principal Russell Gordon said he felt incredibly sad that almost one in five teachers surveyed felt unsafe in the classroom.
Mr Gordon, who took over as principal 18 months ago, said he had not had to deal with any serious violence at the college.
"I'm not saying we're perfect and kids don't explode from time to time, but the college believes in restorative justice when issues and tensions do arise to try and repair the harm and make things right," he said.
Otumoetai College principal Dave Randell said two to three years ago there were some concerns with a small group of students but there had been no incidents of serious violence at the school since it introduced its positive behaviour programme. The school has a zero-violence policy and set clear standards of behaviour.
"One of the biggest things which helps is to ensure all incidents of bad behaviour, that includes swearing in the classroom, get addressed as they occur, and students are put on notice that any serious misconduct will be reported," he said.
Secondary Principals' Association president Tom Parsons said the worst incidences of school violence usually involved drugs and sometimes knives.
On one occasion, a student had stolen methadone from his parents and brought it to school.
"The kids came and got me and said, 'You've got to do something about him, he's right off his trolley'."
Violence in schools was on the rise, but this was a reflection of society rather than the schools, he said.
There was too much pressure on schools to keep problem students in class who had been outside the school system - regardless of their circumstances.
Mr Parsons said at times he had felt unsafe on school grounds.
Teachers did not know how to intervene when things got too heated, and felt threatened.
The kids involved usually came from "horrific" backgrounds.
Some should not have been in school. But for every horror story there was another student from a tough background who "made it".
Most schools had good support systems, including psychological support, for teachers.
Post Primary Teachers' Association president Angela Roberts said poorer communities were struggling more and under significant stress: "The decile funding system, while it is a very blunt instrument, it does at least give a nod to the fact those communities need more support."
Education Minister Hekia Parata said the Government had boosted funding programmes to address challenging behaviour in schools.
Survey results
Twenty-two per cent of all secondary teachers have felt unsafe in their own classrooms and 33 per cent in the school grounds and public areas.
Half of teachers from decile 1 and 2 schools who responded to the survey had felt unsafe in school grounds and buildings at least occasionally, compared with 34 per cent of those in mid-decile schools and 23 per cent in high-decile schools.
