Keeping violence out of schools is hard work, a Hastings school principal says.
The Council for Educational Research's 2012 report on the state of our schools found 22 per cent of all secondary teachers had felt unsafe in their classrooms and 33 per cent in the school grounds and public areas.
The lower the school's decile, the more unsafe teachers felt and the worse students' behaviour became.
The report also found 60 per cent of teachers had faced bad behaviour from pupils that seriously disrupted their teaching.
Camberly School principal Pat Watson said staff worked hard to ensure a safe environment for students and teachers.
But the decile one school used to deal with far more challenging children than it had now: "A few of the local identities who appeared in the paper quite regularly in the court sections were ex-pupils of the school [and] were quite violent."
Much of the behaviour could be traced to students' home life, and whether they had boundaries, Mr Watson said.
But a new system of values brought in to replace a list of rules had helped curb violent behaviour.
"Values of respect for yourself, for others and for property ... leave no loopholes for kids to escape through," he said.
The key was to develop systems to identify problems early on, and resolve them quickly.
"Any place where you've got a large group of children or human beings, you're going to have a little bit of conflict."
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.
Too much pressure was put on schools to keep problem students in class who had been outside the school system - regardless of their circumstances.
"They don't all come along with a lunch box and pens, with an attitude ready to learn."
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.
"Some of these students are 17, 18 years of age - bigger than me, bigger than you," he said.
"Do you leave them to fight or do you break up the fight?"
The kids involved usually came from "horrific" backgrounds. Some should not have even been in school, he believed.
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, in place 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," she said.
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.