Cellphones will be banned from schools if the National Party is elected in October, but the Secondary Principals Association says the plan is unworkable and unnecessary.
National Party leader Christopher Luxon told Morning Report the ban is one of the ways the party will lift "abysmal" achievement in New Zealand schools.
Declining achievement in schools has raised alarm in recent years and last month official figures showed that 15 percent of school leavers in the past year did not have any NCEA qualifications.
Last month the UN also released its report, Technology in Education, and found cellphones distracted students and had a negative impact on learning in the 14 countries studied as part of the report.
"What are common sense practical ways to improve student learning? One of them is to actually ban mobile phones," Luxon said.
"What we're hearing from parents and teachers and what we're seeing in the research is that phones are incredibly distracting and disturbing and they are getting in the way of student achievement."
Luxon said some schools were already enforcing bans well already.
He pointed to examples of students leaving phones at reception and then retrieving them at the end of the day.
"Other schools actually drop them into pouches in their homerooms, [at] other schools the phones must be off and put away in bags and they're away all day."
Countries like Australia already had similar bans in place which worked, Luxon said.
"We've seen that in Australia where they've implemented something similar in all the states ... essentially and it's worked well."
"Not all schools are doing it and actually some principals have come in and said 'it makes our life easier if you come in and actually do that as a nationwide ban'."
But Secondary Principals' Association president and principal of Papatoetoe High School Vaughan Couillaut believed the plan was not necessary.
"[There's] not a whole lot of students walking around at interval and lunchtime, banging into lamp posts and buildings because they're totally distracted by their cellphones.
"Actually what's best is to empower schools to make decisions that are right for them and their community.
"I don't think central [government] controlling banning is the way forward."
Students were not allowed to randomly use their phones at Papatoetoe High School, there were situations where it was appropriate to use them, said Couillaut.
"In some lessons they're away and you don't see them the whole lesson and other lessons they might be engaged in videoing [a classmate] doing a speech or performing at sport.
"A piece of legislation that bans [phones] won't instantly stop [inappropriate use] overnight, it will create conflict, it will create a legal requirement for us to confiscate rather than to educate and train students on how to use things appropriately."
Then there were the practicalities of enforcing a ban with smart devices like watches, he said.
"The practicalities, particularly in a large urban high school, of taking devices off students en masse are just not worth thinking about."
Couillaut gave the example of Mt Albert Grammar which has 3000 students.
"If it took one minute to take a phone and process it off a student at the gate, that's 3000 minutes of human resource to get everyone's phone off them in the morning, 3000 minutes in the afternoon, 6000 minutes of phone policing, there's no time for Maths and English."
But Luxon dismissed that.
'This is not rocket science ... If a school principal can't work out how to actually comply and enforce with the programme, there'll be some other issues going on in that school."
'It's really helped me to focus more' - Wellington Girls' College student
Wellington Girls' College year 12 student Tessa Gilhooly told Morning Report that school rules recently changed around phone usage and it had made a difference.
She said mobile phones now have to be stored away during class, only to be taken out during interval and lunchtime.
"We walk in and there ... a pocket thing on the wall and everyone has to place their phones in."
Gilhooly said the teacher then counts the number of students compared to the number of phones to ensure everyone has put theirs in.
"It's really helped me to focus more and I think it's a really good move.
"[In] the beginning I had a bit of a negative reaction but the experience has been really positive so far."
But she was against a blanket ban where she would not have access to her phone the entire day.
Phones were useful for taking photographs of notes on the board and taking a break on your phone during interval and lunchtime was necessary for her brain to focus, Gilhooly said.