Auckland's rapid population growth is causing overcrowding in schools and affecting teachers' ability to do their jobs, principals say.
Since 2014, Rowandale School in Manurewa has added 144 students to its total roll - an increase of nearly 30 percent.
The Ministry of Education says Rowandale School was given six relocatable classrooms last year to help cope with the increase in students.
The school's principal Karl Vasau said until the end of last year some classes had a student-teacher ratio greater than 35-1 and that was putting huge pressure on teachers.
"Our children already start school behind the eight ball. Some of our children come in without the basics, and so our teachers have to work extremely hard. But when you've got 35 to 37 children in your classroom, it's very difficult."
Mr Vasau said Rowandale had not had a library in over five years; the school was so pressed for space it had converted its purpose-built library into a storage room for teaching resources.
A teacher shortage in Auckland had also put pressure on class sizes after a teacher quit at the beginning of the current term, he said.
A replacement teacher couldn't start til the beginning of term four.
Mr Vasau had a meeting with the Ministry of Education today and discussed the school adopting a zone boundary to allow it to control its roll size.
Rowandale is not the only school in this position.
Manurewa East Primary School principal Phil Palfrey said he was considering drastic action to solve the school's space problems.
"I've been there for 17 years - it's our highest roll for this time of year.
"We're short of a classroom right now, so we need to get a classroom in pretty quickly - there's even a chance we might have to convert our hall into a classroom, just for now."
He said teachers were being asked to do the same work, with more students, in less space.
The principals' representative on the Education Institute, Lynda Stuart, said it was a nationwide issue.
"We've got some schools across the country - and also specifically in Auckland - that are experiencing overcrowding in their schools, because they've reached ... over-capacity for the buildings they have."
In a statement, the Ministry of Education said there was still more space than students at Auckland schools, but admitted about 60 of the city's 550 schools needed more room for students.
"We have a plan in place for each of these schools, as students and staff need a good environment for learning," the statement said.
"By early next year 230 new classrooms will be built at schools across Auckland. We have built 13 new schools in Auckland in the last 10 years, and another six new schools are currently underway. Between 2014 and 2019 we are building enough space for another 17,000 students."
Associate Health Minister Nikki Kaye told Morning Report there were parts of Auckland that had experienced the higher end of growth projection, but the ministry had been delivering classrooms and building new schools as a result of that.
Ms Kaye said the ministry was at least two thirds of the way through building the more than 230 new classrooms, and 50 replacement classrooms, announced last year. She said those classrooms represented around 6000 students, but the ministry was building space for 17,000 students by 2019.