Schools are increasingly putting students under closed-circuit television surveillance to cut bullying.
The practice is suggested in new Ministry of Education bullying prevention guidelines - and some schools have already put cameras near toilet blocks after learning bullied children were avoiding them for fear of getting bashed.
One Auckland principal reportedly keeps an eye on monitoring screens in their office.
The bullying prevention document is the work of an advisory group including the Children's Commissioner, police, education unions, principals' associations and cyber-safety organisation NetSafe.
Other practical advice to schools includes stressing to students that as bystanders they can either enable or defuse bullying, and how to create confidential reporting systems. Schools are asked to consider whether there are areas where students feel unsafe, and are given advice on how grounds can be changed to reduce bullying.
"Ensuring areas are easily accessible, well lit, and regularly supervised/monitored (using closed-circuit television) will help reduce the likelihood of bullying," the report says.
Patrick Walsh, who helped to write the guidelines as an executive of the Secondary School Principals Association, said he was surprised by the number of schools that used CCTV to combat bullying.
They often put cameras outside toilet blocks, because student surveys revealed victims of bullying often avoided those areas. "They don't go to the toilet all day because they are afraid to go into the toilet because they'll be assaulted."
The Office of the Privacy Commissioner says schools must display "notices about the presence of cameras" and "have clear policy guidelines about storage and access to the information collected".
Mr Walsh, principal of John Paul College in Rotorua, said there was a balance to be struck, but privacy concerns were minor compared to the bigger picture.
"I think the vast majority of students and parents would be happy to have more cameras in a school if it meant that the school was going to be a physically safe environment."
Whangarei Boys' High School has used CCTV for many years to deter misbehaviour among students, says headmaster Al Kirk.
"We've got them in different places around the school, but primarily at entrances to the loos and stuff like that to just ensure that if there was any nonsense going on we have a rough idea [and] can track them."
Incidents which actually required viewing of the footage probably occurred about once a term, Mr Kirk said. "We didn't introduce it because we had a problem. We introduced it it to ensure we didn't get problems."
Ministry of Education executive Rawiri Brell said security cameras were most often used to guard against vandalism.
They were funded through a school's property budget and administrators were not required to report they had been installed.
"It is up to schools to decide, in consultation with their parent community, what measure they take to minimise [bullying]. We will support them in this process."
The Human Rights Commission says children have a right to be free from violence and abuse in school. "Our schools need support to ensure this becomes a reality," said chief Human Rights Commissioner David Rutherford.
- additional reporting: Teuila Fuatai