If charter school opponents are looking for someone to blame, then perhaps they should point the finger at David Guggenheim, the documentary-maker who directed Oscar-winning climate change doco An Inconvenient Truth.
Guggenheim's 2010 documentary, Waiting for Superman, was hugely influential on Act Party members and libertarians worldwide, and is often cited as proof-positive of charter school virtue.
The film tells the story of five children entering a lottery to win a place in a charter school.
It's a feel-good movie with plucky, disadvantaged kids, heroes (charter school providers such as Harlem Children's Zone chief executive Geoffrey Canada) and villains (the American Federation of Teachers).
But, as Diane Ravitch, research professor of education at New York University, noted in the New York Review of Books, the documentary is riddled with statistics that are plain wrong.
The movie ignores the 37 per cent of charter schools performing worse than public schools, charter chains involved in scandalous real estate deals, charter chief executives accused of embezzlement and the expulsion of non-performing students to boost school scores, Ravitch writes.
Canada, who runs two charter schools and provides social services to Harlem families, is paid US$400,000 ($530,000) and has assets of more than US$200 million under management due to philanthropic backing, she continues.
Despite riches beyond the dreams of public schools, more than half of his fourth graders (nine or 10-year-olds) were not proficient in reading in 2010. "Canada kicked out his entire first class of middle school students when they didn't get good enough test scores," Ravitch says. "Even the best-funded charters with the finest services can't completely negate the effects of poverty."
In the UK, Warwick Mansell, a former journalist at The Times Education Supplement and an expert on school qualifications, believes the "education world" is now splitting between those who favour US-style reforms (US, Britain, New Zealand) and others such as Canada, Germany and Finland which "see the future as less about confrontation [and] reform and more about supporting teachers and schools".
"I've always been a bit of a sceptic," Mansell admits. "Isn't there a danger that any government pushing this new, favoured type of school undermines confidence in existing schools?"
Ian Leckie, national president of teachers union NZEI, believes charter schools erode public confidence in state schools.
Charter schools deliver demonstrably poorer results, Leckie says, citing the CREDO national study conducted by Stanford University economist Margaret Raymond.
Why would New Zealand import the charter school model, Leckie asks, when there is no overseas evidence of improvement to other countries' education systems? "We don't subject our children to failed overseas experiments."
Leckie believes Catherine Isaac's charter school working group is driven by ideology to impose a charter school system on New Zealand. "It's not evidence-driven or educationally driven."
Leckie, who spent 14 years teaching in a decile 1A school, also contends the actual motive is union-busting. "If that's the real agenda, let's just say that's the real agenda."
For her part, Isaac expresses a faint hope that charter schools won't be seen as "an assault on teachers".
"I would be the last person to trash public schools," she says. "We've got wonderful schools and wonderful teachers."
But there are children coming out of some schools whose lives are ruined before they even start, she says. "Some overcome a bad education but many don't. This is a small initiative that may be effective for children currently failing."