Mr Key revealed he would be happy for his children to be taught by professionally trained rather than registered teachers.
A "small number'' of charter schools, the first in New Zealand, are set to open in 2014.
Education Minister Hekia Parata and Associate Education Minister John Banks this morning announced the framework for the country's model of charter schools.
Mr Banks said the schools would be able to negotiate the percentage of registered teachers they want to employ because "sometimes there are people who can make a valuable contribution to teaching who won't necessarily be registered teachers.
"We want the best people in front of the classrooms for these young people we're reaching out to,'' he said.
Non-teaching and unregistered employees will undergo police vetting, and Mr Banks said there would be a "high level of accountability ... and transparency'' for partnership schools.
Mr Key said some teachers already in New Zealand schools, such as technology teachers, often had trade backgrounds rather than as qualified teachers.
Ms Parata said the charter schools would target the one-in-five students who currently leave school without an appropriate education or qualifications.
The schools will be allowed to reshape the national curriculum but will be required to meet education targets set by the Government.
Legislation will be put before Parliament this year, and formal requests for proposals from potential charter school sponsors will be called for once the legislation passes.
Some may be existing schools that submit to register as partnership schools but others will be entirely new entities.
Mr Banks said applications to run a partnership school would be vetted by an approvals body, and the Education Minister would give the ultimate approval.
The Government anticipates submissions from a mixture of iwi, church groups and private companies, some of which will look to work towards a profit.
Partnership schools must report against National Standards for years 1-8 students and must offer NCEA or an equivalent qualification recognised by industry and tertiary providers in New Zealand.
But the New Zealand Education Institute says allowing unregistered teachers to take classes at charter schools is "a major step backwards for quality education''.
The announcement today by the Government that charter schools will be allowed to negotiate how many registered teachers they employ has "no educational merit'', NZEI president Ian Leckie said.
Mr Leckie said he can't imagine any parent wanting to send their child to a school that employed unqualified teachers.
"No one would want to be treated by an unqualified doctor and we don't employ unqualified engineers so why should we have unqualified teachers in our schools?''
Labour's education spokeswoman Nanaia Mahuta said the decision was "a disgrace''.
"The National-Act Government claims it wants to improve teacher quality. But allowing unregistered teachers into the classroom will do the exact opposite,'' Ms Mahuta said.
"Our kids deserve trained professionals who know how to get the best out of them.''
New Zealand First Party education spokeswoman Tracey Martin said the Government's renaming of charter schools - now referred to as partnership schools or kura hourua - was "just like putting lipstick on a pig''.
"At the end of the day it's still a pig,'' she said.
"Under the Government's cosy arrangement, sponsors can operate multiple schools across New Zealand, skimming educational dollars from taxpayers to pay dividends to their shareholders.''
The Green Party said vulnerable pupils need ``a strong state education system'', not to be forced into charter schools.
Education spokeswoman Catherine Delahunty said disadvantaged students who are "unlikely to be able to afford to bus to other schools'' will be "stuck with whatever ideology their sponsor [the group that sets up the charter school] wants to run the school by''.
