The Secondary Principals Association says students are increasingly bringing weapons such as knives and screwdrivers into schools.
Stephen Hose, 53, was stabbed while teaching a maths class at Te Puke High School on Monday morning.
Mr Hose was wounded in the neck and left shoulder in front of a class of 23 Year 9 students.
Police have questioned a 13-year-old student, who is now in the care of Child, Youth and Family pending a family group conference.
The stabbing was the second on a teacher in just over a year.
Secondary Principals Association president Patrick Walsh told Morning Report that assaults on teachers are rare, but rapidly increasing.
Mr Walsh says teachers need more powers to protect themselves in light of a rise in violence. He says it is unclear whether staff are allowed to search students under the Bill of Rights.
The Post Primary Teachers Association says schools do not have enough resources to deal with violent pupils.
Education Minister Anne Tolley says measures are in place to reduce violence at schools.
Mrs Tolley says a $45 million action plan launched last year is helping to reduce disruptive behaviour, but communities and families also have to take responsibility for young people.
Support for students
Te Puke High School principal Alan Liddle says Victim Support and the Special Education Traumatic Response Team worked in the school on Monday.
Mr Liddle says he will meet the parents and caregivers of the students in the class on Tuesday and support for students who need it will be ongoing.