Violent and dangerous behaviour sparked more than 200 stand-downs, suspensions and permanent student dismissals from Bay of Plenty schools this year.
Education Ministry figures, released under the Official Information Act, show most were for physical assaults on staff and students.
More than 100 violent incidents resulted in disciplinary cases in the year to October 16, with five students - all aged under 16 - permanently dismissed from school.
Bay of Plenty figures relate to schools in the Western Bay, Whakatane, Kawerau and Opotiki.
Brookfield Primary School principal Robert Hyndman said the number of violent incidents in schools varied between years.
"This year we've had no stand-downs and normally we have three or four. So for us it's been a good year."
But some student year groups were more challenging than others, Mr Hyndman said.
Last year a teacher and three students were attacked in an incident at Tauranga Girls' College. One of the students involved, Fay Baylis, told the Bay of Plenty Times she had been "strangled" in the attack.
However, disciplinary cases for violent and dangerous behaviour in the Bay of Plenty have dropped in recent years - down 23 per cent since 2010.
In Northland there were about 560 disciplinary cases for violent or dangerous behaviour this year, and 390 in Hawke's Bay.
Mr Hyndman, who is also head of the Western Bay Principals' Association, said attitudes towards violence had changed.
"When I look back a generation or two, parents might have told the child to harden up when there was name-calling or those sorts of things.
"As a society, we are more prepared to say that is unacceptable."
Nationally violent and harmful behaviour offences accounted for more than half of all primary and secondary student stand-downs, suspensions and permanent dismissals this year.
Of the 17,558 disciplinary cases, nearly 9000 were for violence, abuse, dangerous behaviour or weapons offences.
Post Primary Teachers' Association president Robin Duff said some schools were reluctant to impose disciplinary action against students, or report them to the ministry. They feared being judged by parents on the number of violent incidents that occurred.
"There is some pressure on principals and boards to keep it [violent and dangerous incident reporting] in-house."
New Zealand Principals' Federation president Paul Drummond said removing pupils from school was a last resort.
Many schools had introduced programmes aimed at promoting positive learning cultures and discouraging anti-social behaviour.
Student disciplinary cases for violence and dangerous behaviour had dropped significantly in recent years, down 30 per cent since 2009.
But the decline may not necessarily correlate to less violence in schools, Mr Drummond said. "Schools have put a lot of resources into managing serious behaviour and whether or not that's reflective of a decrease in anti-social behaviour outside the school gate, I just don't know.
"There are still obviously instances of serious misconduct that are challenging to manage."
Many violence offences involved male students in their intermediate and early high school years, Mr Drummond said.
"Just by their normal maturation they are starting to challenge and it's also a time when some children are starting to be disengaged from school."
Sadly, violence among primary school students was not uncommon either, he said.
"Reasons for that behaviour are complex."
Dysfunctional families, psychological and physical abuse and problems with alcohol and drugs were often at play, Mr Drummond said.