With just weeks to go before the Government selects the first partnership schools, new research shows the performances of similar schools in the United States are improving.
The Stanford University study says nearly a third of charter schools in the US are out-performing public schools.
The research says 29% of American charter schools were better at raising student achievement in maths than comparable public schools in 2011, up from 17% in 2009. Some 31% of charter schools were significantly worse than public schools, down from 37%.
On average, children do better in reading at charter schools than at public schools, but about the same in maths.
The New Zealand Educational Institute says it shows that even with additional funding from private sources, charter schools make little difference and the Government is wrong to introduce the publicly-funded private schools.
