The Ministry of Education has challenged principals' claims that schools have been forced to send children home due to lack of teachers.
The ministry told RNZ there was no evidence that had happened.
Principals insisted it had, but admitted it was rare and occurred due to a combination of unfilled vacancies, staff illness and lack of relief teachers.
One told RNZ staffing was chaotic and schools were "cobbling together" solutions on a daily basis to ensure they had enough teachers, including obtaining Limited Authority to Teach for support staff so they could take classes.
Another said their school asked parents to collect children early once in term two because some teachers were too sick to continue working and there were no relief teachers to replace them. Unfilled vacancies were not a factor, however.
But Greymouth High School principal Sam Mortimer told RNZ unfilled vacancies had contributed to her school's decision to roster students home several times in term one.
"It really started in week six of term one where we had to roster home our seniors that day. And from then on we had to roster for a few weeks off and on a year group every day," she said.
Mortimer said it was a big and difficult decision prompted by staff illness.
"We had absolutely no choice. We had not enough teachers and we hardly have any relievers," she said.
The school had already been doubling up classes, with 60 students in the school library because there was nobody to cover their classes.
Mortimer said at the time the school was covering two unfilled vacancies by asking part-time teachers and a relief teacher to work full-time.
If the vacancies had been filled the school could have avoided at least some of the rostering home days, she said.
The Education Ministry said teacher availability varied across the motu, and some schools were facing challenges recruiting the teachers they wanted.
Retention data showed a reasonably stable number of teachers in the system, the ministry said.
"The data does, however, indicate an increased number of teachers moving jobs within the sector, rather than a net loss of teachers to the overall system," it said.
The ministry said there was nothing unusual in the number of teachers going overseas and despite "a massive global teacher shortage" New Zealand was itself attracting foreign teachers.
"The government has invested in initiatives to boost domestic supply and attract qualified teaching staff from overseas, including an additional $24 million in both September 2022 and Budget 2023," the ministry said.
"Our initiatives include making it easier to return to teaching by making the Teacher Education Refresh programme free, getting teachers into the classroom more quickly by speeding up processing of domestic and overseas teacher applications, scholarships for people making a career change to teaching, supporting schools to recruit overseas teachers with the Overseas Relocation Grant and the Overseas Finders' Fee; and 'navigators' who provide schools, kura and overseas teachers with 1:1 support through the overseas teacher recruitment process."