US education secretary Arne Duncan this week warned his English counterpart Michael Gove that he will have to close unsuccessful free schools.
Mr Duncan, who was in the UK to exchange education policy ideas with the Government, said some schools will "not work out", but that it was all part of the "learning curve".
Speaking from Mossbourne Community Academy in east London, Mr Duncan said many charter schools in the US, on which Mr Gove's free schools are partly based, were forced to close because they were failing.
"We saw in the US that anyone who wanted to open a school got the right - that doesn't work," Mr Duncan said. "You must have a high bar to entry, and pick the best from the best. One should not let a thousand flowers bloom."
In Ohio, more than 60 charter schools were forced to close in the last five years due to issues such as financial mismanagement and low pupil numbers. A further 31 schools have been put on a "watch list".
"Will you get every one right? No, of course not," said Mr Duncan. "But I do think there will be a higher rate of success over here than the initial charter school movement in the US because we were a little loose in the front end. Where you have clear accountability at the back end, if one or two don't work out that's part of the learning curve."
Mr Duncan added: "The goal is not to be perfect. Perfect can be the enemy of the good here."
The US education secretary's comments were criticised by Labour and teachers' union ATL, which said it was children's education that was at risk.
ATL general secretary Mary Bousted told The TES: 'It may well be good for the Government, but it's not part of a very good learning curve for the pupils, is it?
"(The free schools initiative) really is a suck-it-and-see policy. It seems to be a cavalier approach to education from this Government, and one that is entirely predictable."
But a Department for Education spokesperson said: "We have set a high bar for all proposals to prove they have outstanding management, clear demand from parents, and an effective plan for their day-to-day running. We will never hesitate to step in where any state-school is under-performing, whether they're academies or local authority-maintained."
Shadow education secretary Andy Burnham said: "Free schools are an ideological experiment with few checks and balances. Free schools that fail could destabilise other local schools. For many parents this is a roll of the dice with their children's future they will not want to take."
GOVE LAUNCHES #163;110M IDEAS FUND
Also at Mossbourne Community Academy, Mr Gove unveiled a #163;110 million Education Endowment Fund - his own version of US president Barack Obama's Race to the Top programme. It will enable local authorities and academy sponsors to bid for money to pay for innovative education ideas to raise attainment.
Mr Gove said: "The fund will make schools and local authorities compete to help the poorest."