Many schools with phone bans already in place report students are happy with the measure.

Cellphones will be banned from schools if the National Party is elected in October, with leader Christopher Luxon saying the ban is one of the ways the party will lift students' "abysmal" achievement.

At Queen Margaret College there is a no cellphone policy, but despite that students are allowed to carry their phones with them - and are trusted not to use them.

Year 13 student Eve Robertshawe says it means children learn how to appropriately use their phones.

"It's actually really effective because once we get out into the real world and we have a career, our boss isn't gonna take our phone off us at the start of the day."

Fellow student Avani Aiulo, Year 10, says not using her phone has helped with her learning.

"I think I'm more focused and I'm more engaged in what my teachers are talking to me about, without using my phone."

Year 6 student Samira Peake says people not looking down at their phones made it easier for her to make friends when she first transferred to the school

At Scots College, middle school students need to keep their phones in their locker, while senior students can keep their phones on them.

Year 10 student Jack Hendricksen says he found the policy "a bit weird" after coming from other schools that allowed phones. But he says not being able to use his phone means he spent more time outside at school.

Imogen Oscroft, Year 8, says the policy did make it harder for students and parents to contact each other, but not impossible, while Caitlin Horn (Year 10) says people communicate more when they are not looking down at their phones.

Students at both schools reported being able to use their phone in classes where teachers deem they add value.

National also says it will make exemptions to the phone ban if a student needs it for health reasons or as a learning aid.

'Kids are back to being kids'

While Secondary Principals' Association president and principal of Papatoetoe High School Vaughan Couillault told Morning Report a total nationwide ban is unworkable and unnecessary, that has not been the case at Otago Boys' High School, according to rector Richard Hall.

The school banned openly using cellphones early last year - including during breaks. Hall says the ban is going well.

"I've been really pleased with the way it's been adopted by students and the community," he told RNZ's Checkpoint. "Couldn't be happier with it, to tell you the truth."

There has been two main changes, he explains.

"Kids are back to being kids - playing in the playgrounds, talking to each other, all of those sorts of things that people at my extreme age did when we were at school.

"The second thing is the number of incidents of cyber bullying that we have had, including students and staff, have dropped through the floor. Before we'd have incidents where boys would be videoed, photographs would be taken without their permission, and sometimes staff too, and those would be uploaded with obviously pretty dispiriting messages. That really while it's not zero, it's certainly a lot less than it's ever been."

Hall says some students are apprehensive at first, but did not take long to understand why the ban is there.

"I think when you explain it to teenagers and you understand all of the research around what's coming through their phones, the influence of Andrew Tate and people like that that we continually have to fight in schools, they get it straight away."

Students can take phones to school - so they can call parents after the final bell for pickups, for example - but they have to stay in their bags during school hours.

"It's often in your bag from the moment you enter our grounds to the moment you leave. If it's in your pocket, even if you're not using it, it's mine," Hall says.

The first time a student is caught using their phone, it's confiscated overnight; the second time for a week; and the third, a conversation with their parents would result.

Hall says that results in far less work than having to deal with the consequences of unabated social media use.

"I don't spend much time doing it at all really, in the main. My response to that would be, what was the amount of time I was spending with serious discipline incidences and interviewing parents and interviewing boys, when teachers or boys were having their photographs taken without their permission?

"That was far in excess of what I'm doing now when I'm telling a boy to give me his phone, hand it over and he can collect it tomorrow."

He says if the ban came not from school officials, but the government, his job would be even easier.

"I think it would be easier as a principal… to say hey look, to a parent or a boy or a child who's upset with it, 'Hey, it's government policy. Just following the government policy.'"

-RNZ.