The Government's backdown over school funding changes was a political, rather than educational decision, critics say.

Announcing the U-turn on class size funding changes, Education Minister Hekia Parata said there was a "disproportionate level of anxiety" among parents about the plan.

She had tried to sell the $174m cut to teacher funding as a "trade-off" for higher teacher quality, including by a $60m boost for teacher recruitment and training.

"It is clear that that is something that has been rejected by teachers and by parents and so we have to look at a different set of trade-offs," Parata said.

Speaking in Hamburg, Prime Minister John Key said he still felt the proposed changes were right and the U-turn had only been caused by parents' negative perceptions of them.

"We were effectively saying to the sector 'here is quite a lot of cash to fund [teacher] development [funded] by making what we think - I still think - is a very modest alteration of class sizes'. But what is clear is that parents don't see it as modest and in the end perception is reality."

It had become "blindingly obvious" parents would not wear the policy and that was why the Government had backed down, Key said.

But education experts insist the plan was misguided.

Canterbury University Associate Professor Lindsey Conner said the "underlying premise" of a "trade-off" was "a little bit false".

"If you have higher numbers of children in a class, it's actually very counter-intuitive to what students and parents and grandparents and educators know about the amount of time teachers can give attention to individuals," Conner said.

"I think there are other ways of developing efficiencies rather than slashing teachers. That's not the way to do it. To achieve the outcomes that they want, that is not the way to do it."

Labour leader David Shearer said it was clear the backdown had been motivated by politics, and not because the Government was truly concerned about the impact of the policy.

"Hekia Parata says she decided to reverse the plan following a 'disproportionate amount of anxiety' from parents. This plainly demonstrates that National still did not think that the policy was wrong," Shearer said.

It was "mindboggling" that National could have ever thought increasing class sizes was in any way a good idea.

"The Government still doesn't get the damage that increased classes sizes will do to children's learning," Shearer said.

Green Party co-leader Metiria Turei said the aborted proposal had destabilised the education system, damaged the faith of the schools sector and caused "enormous angst" among parents.

UnitedFuture Leader Peter Dunne, a support partner of the Government, said bigger class sizes were "a step in the wrong direction".

"I think this is a necessary step ... There is no question that the Government is committed to raising student achievement - it is just a matter of how they go about it," Dunne said.

- © Fairfax NZ News