Competition between schools for students is causing problems in some parts of the country and the education ministry has had to step in.
In areas including Manurewa, Dunedin and New Plymouth, the ministry is helping schools figure out how to share the available pool of children and, where necessary, put enrolment zones in place.
Principals said it was hard to balance schools' autonomy and parents' choice with careful use of taxpayer money.
In Dunedin, falling numbers have left the city's 12 secondary schools battling for enrolments and half of the schools have fewer than 600 students each.
Earlier this year, the ministry insisted one of the schools, Kings' High School, cap its enrolments and adopt an enrolment zone, and it has been working with all 12 schools to develop options for managing their enrolments.
Principal of Bayfield High School Judith Forbes said the schools were all within a 10 minute drive of one another and swings in popularity could have a big impact on enrolments.
"I guess we're hoping that the ministry will be able to come up with some ways that we can operate in a more collaborative framework, than such a competitive framework."
Ms Forbes said without a ministry-brokered agreement, it was possible that some schools would be significantly harmed by roll drops.
The education ministry said it had been holding meetings with principals and boards of trustees because of roll growth in other areas.
In New Plymouth some schools are growing so fast they are bursting at the seams, while others have empty spaces.
President of the local principals' association Michael Carr said the schools had been told the city was one of the fastest growing areas outside of Auckland.
He said the ministry was trying to help them find a solution that took into account the needs of the area's schools.
"The conversation in New Plymouth has been about, as a group of schools, how do we look at this objectively and what are our options? But it seems to us the only option available is for them to impose zones or say to schools 'you're at or over capacity, you need to have a zone in place'."
Mr Carr said the ministry needed to act faster, though he acknowledged it was not a simple problem to solve.
In Manurewa, the ministry has turned down several requests from primary schools' to extend the number of year levels they teach while it figures out what is happening with the local population of school-age children.
President of the principals association Karen McMurray said some schools were full, while others had space and it had created a bit of tension.
"It's a hard one because you've got the board of trustees and then you've got the ministry looking at a bigger picture and the demographics over a longer period of time and a wider area and trying to make sure that they can use the resources that they've actually put in place as well in terms of upgrading schools."
Ms McMurray said the Manurewa population was growing, but without the ministry's intervention it was unlikely the growth would be spread evenly among schools.
"You could see a lot of empty schools and a lot of schools that are burgeoning with roll growth and it would just be a huge waste of resource."
She said the schools that applied to extend their year levels, from Year 6 to Year 8, wanted to provide eight rather than six years of bilingual education because research showed that worked best. However, allowing the extension to higher year levels would hurt the rolls of local intermediate schools.
The Education Ministry's Katrina Casey said working with school leaders to manage changes in student numbers was part of the ministry's daily business.
She said it was also talking to schools about roll growth in Wanaka and Cromwell, and was planning similar work in Palmerston North.