Mr Newman, who is also principal of Hora Hora Primary School, says principals will have to suspend kids with severe behavioural needs when they cannot get the required help or services like extra funding for teacher aides and counselling.
Mr Newman is referring to children who receive some funding for behavioural needs and are "totally out of control", rather than children who are sometimes naughty.
Some of these children were only getting two hours teacher aide funding a day despite being at school for six hours.
"They don't become little angels for the other four hours.
"A child that walks up to another volatile kid without any warning. Grabs them around the neck, throws them off the chair.
"A child that threatens to stab another kid with scissors and races back to the classroom to get the scissors.
"A child that had to be restrained because they had a knife in their hand and they wanted to stab a teacher. Those are some examples," he said.
Mr Newman said principals were using government operations funding to cover the additional four hours to ensure the safety of the student, other students and staff.
"My belief in suspension and expulsion is that it's a waste of time. I have to think about my staff who are stretched to their limits, I have to think about the safety of other students. But I need to think about why I cannot give these students the help they crucially need."
David Wales, head of learning support at the Ministry of Education, said spending on teacher aides to support children with behavioural issues rose 20 per cent in 2016 in Northland, compared to the year before.
He said the Ministry helped 250 children with behavioural issues in 2016 in Te Tai Tokerau, compared to 239 the year before and said there was nearly 40 specialist staff, like psychologists and behavioural experts, in the region dealing with children with additional needs.
"We appreciate that Northland schools do face challenging issues with children with behavioural needs. That's why we've increased our support to schools dealing with these issues," Mr Wales said.
Bruce Crawford, principal at Hikurangi School, said he supported Mr Newman.
"I have a child at this school who can only attend for three days a week because they haven't got the money for five days a week.
"A lot of these kids with high anger issues need professional counselling. The Ministry of Education psychologists are scarce as rocking horse poo and the ones that we do have are hugely overworked and have huge caseloads," he said.
Robert Clarke, principal of Whau Valley School, said suspending kids was the absolute last resort but that would be the only option.
"We're of the inkling that society should judge itself on how it treats its most vulnerable and we're not doing a particularly great job. The schools are doing a great job with the resources they've got but that is nowhere near enough."
