Unexpected roll growth has left some Auckland schools scrambling for teachers even though they thought they had enough staff just before the school year started.
Schools in high-growth areas, such as Beach Haven School on the North Shore, say they are at full capacity.
"There's only so many broom cupboards one has," said Beach Haven principal Stephanie Thompson.
Other schools have hired overseas teachers to fill staffing gaps and say they need more support to teach the immigrants about New Zealand's curriculum and cultures.
Education Minister Chris Hipkins said about 900 teachers had now been recruited from overseas since September 2018.
The shortage has been deepened by a new initiative to fund 623 learning support co-ordinators from the start of this year.
Thirty-five of those roles are still being advertised in the Education Gazette, and many of those already appointed have created vacancies for their previous teaching jobs.
Altogether the Gazette lists 475 vacancies in primary, intermediate and secondary schools nationally, up from 370 last month.
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Thompson said her roll had jumped by 80 this year, partly because of state housing projects where two or three new homes are being built where only one existed before. As more 5-year-olds start through the year, the school will run out of space.
"We are just a handful of students short of capacity now," she said. "I have asked for more."
She has used a scheme that lets Auckland primary principals hire a beginning teacher from the start of the year even though the roll was not expected to justify the position until more 5-year-olds started school later.
"That will solve the immediate roll growth, but what we will look like in six months' time is another story," she said.
Albany Senior High School principal Claire Amos said population growth had also added 100 extra students to her school this year, but she has found enough teachers.
Papatoetoe East Primary School principal Paul Crowhurst said he had as many students already as he had planned to have next term. He has brought in a relieving teacher to take the extra class fulltime.
"We have a little bit of temporary housing in our area now and that has made our roll shoot up," he said. "We probably have a dozen kids in motels."
However Hipkins said the national picture was actually slightly below expected growth.
"The advice I've had is that the forecast roll growth might be a bit lower than expected," he said.
"Looking at the national trend doesn't necessarily tell us the full story [regionally]. I am monitoring roll growth problems closely because it affects not just teacher supply, it has an impact on the overall spending bill that we have to pay."
Papatoetoe Intermediate principal Pauline Cornwell said she hired three teachers from South Africa last year and four more this year, plus one from Fiji, but they needed more support than the half-day a week of extra staffing for 10 weeks that a school gets for a new overseas-trained teacher.
"We have got teachers who started working at our school a week after they arrived in the country," she said.
She said the ministry had provided an online training course for the overseas teachers, but they needed help from their mentor teachers to understand some of the language and concepts.
"Most of the overseas teachers that we've had have started it and given up and said, 'I'll go back to it,'" she said.
Lauren Hartley, one of the South Africans hired at the school last year, said other teachers came in before school started to help her last January but the change was still huge.
"It was a massive shock because of the culture difference. The big thing I would have liked was understanding the cultures of each child," she said.
The curriculum was also very different.
"The South African curriculum is very broad. You are basically told you must teach this and this and this," she said.
"Here we are told that you break people into groups and you actually focus on what they need, not the whole curriculum."
Cornwell said overseas teachers needed the same extra staffing support as NZ-trained beginning teachers, who bring a full day a week of extra staffing for their first year and half a day a week for their second year.
However Hipkins said schools also needed to "make a contribution towards inducting overseas-trained teachers into NZ schools".