The schools are privately run and publicly funded. Five opened in 2014 and four this year, all in either Auckland or Northland.
Initial ERO reports have shown that several of the nine schools are performing well, although Te Kura Hourua ki Whangaruru in Northland is still under threat of closure due to ongoing governance and financial problems.
The first in a multi-year evaluation of the schools was released today. It focused on three of the five first-round schools. Consultants reviewed the literature on the schools and conducted site visits where they spoke to staff, students and parents.
Key areas of innovation were the governance and management structures, where specialists were brought onto the board rather than parents; and where the administration and academic functions were separated, leaving principals to focus on teaching and learning.
There were also positives around staffing and teaching, particularly with class sizes, the report said.
"Sponsors and management told us that the relatively small school/kura rolls and small class sizes enable staff to build and maintain close relationships with students," it read.
It said small numbers allowed for good pastoral care and a focus on the individual.
Students also enjoyed the small sizes, with one saying: "We get to know each other and our teachers well."
The report said maintaining those small class sizes may be a challenge as the schools grow.
The evaluation found having strong vision was also important, and that the funding model encouraged innovation and "risk taking". Charter schools are funded in bulk, unlike state schools which receive specific funding across a range of expenses - staff, buildings, operations, etc.
The model was recently adjusted after criticism it was paying the schools at a much higher rate than in the public sector. Charters will now receive lower start-up costs and will be expected to partner with outside investors.
The evaluation said barriers to the success of the charter schools included a negative public perception of the schools, some limited facilities and a short lead-in time to opening.
Student feedback about the schools was mainly positive, with some saying their old schools were "dumb" or "boring" by comparison. However others said they missed singing, their school library and sports fields.
Act MP David Seymour, who has responsibility for the schools in his role as Undersecretary for Education, said he thought the report was fair but was mindful it did not include quantitative analysis.
He said the schools had maintained small class sizes by doing things like economising on buildings and music resources, and using community facilities like pools and parks that are otherwise underutilised while kids are at school.
Green Party education spokeswoman Catherine Delahunty said it was "so ironic" that small classes were identified as making a difference for these children. "Why not all children?," she said.
"After all the extra funds given to these schools the most we can say is that small classes work better and we knew that before."
National Secretary of the primary teachers' union NZEI, Paul Goulter said he was concerned that while government said part of the reason to set up charters was to lift system performance for priority learners, that was not in the report.
"There is no evidence about whether the model is able to be scaled up. It's a very narrow look at it."
