Education Minister Hekia Parata says no school will lose more than two full-time teachers (FTTEs) as a result of increased student-teacher ratios.
She said 90 per cent of schools would gain or have a net loss of less than one FTTE as a result of the combined effect of the ratio changes and projected roll growth.
"We have examined the effect on the other 10 per cent of schools, and some would be affected more than we would accept."
She said schools will be given a guarantee that their staffing entitlement will not be reduced by more than two FTTEs over the next three years as a result of the policy changes.
Ms Parata conceded that the Ministry did not intend the policy to undermine the specialist technology provision at Levels 7 and 8.
She said the Ministry and the sector working group will ensure that technology provision continues.
"Either way no school will end up with more than two FTTEs fewer than they currently have, because of these policy changes,'' she said.
She said any additional cost from these changes will be met from a contingency set aside by the Ministry to manage the transition to the new ratios.
Ms Parata described the move by the Government as "good news,'' in Parliament today.
Prime Minister John Key said the ministry wrote to 10 per cent of schools, who faced losing more than one teacher, to tell them there would be a "transition'' period and they would be protected from losses greater than two teachers.
Mr Key admitted the Government didn't communicate the message effectively to parents that the ministry would work on that "transition'' programme.
"There are some parents who are concerned and we're trying to allay their concerns by saying over a three-year period there will be no more than two full-time teachers lost from any school,'' he said.
Mr Key said it had not always been the Government's intention to cap losses at two teachers.
"It was always our intention to work on the transition for the 10 per cent of schools and we were happy to sit down and work with the teachers and work with those particular schools,'' he said.
He said money had been set aside to apply to the transition of the class size changes.
"We are hellbent on wanting to increase the quality of teaching in New Zealand and we think, after a very substantial build-up in the number of teachers in the next 10 years, we've got about the same numbers. If we stayed with the old funding formulas the money would have to go into more teachers, not improving the overall quality, and we stand by that decision.''
The Government announced before the Budget and reiterated on Budget day that it would save $43 million by increasing class sizes.
Ms Parata would not say why the Government had announced it would save $43 million from changing class sizes on, or before Budget day when she said they knew they would to use some of the funds for a "transition''.
"The letter that we wrote to schools made it clear that we would be working with them in terms of that transition and we've brought that forward to provide certainty,'' she said.
Ms Parata said the Government had anticipated the consequences of class size changes.
She said she did not expect schools would react by talking about industrial action at schools as a result of the changes.
Jonathan Tredray of Northcross Intermediate on Auckland's North Shore called the changes "devastating'' and an "absolute nightmare''.
The decile-10 school has worked out it will need to lose up to 10 teachers from a staff of 50 - including three teachers providers by its boards of trustees - and increase class sizes to about 40 to keep its technology subjects.
Green Party co-leader Russel Norman said Ms Parata's announcement was far from "good news''.
"It's an embarrassing admission (the Government) stuffed up.''
He said teacher numbers were capped at last year's levels in the Budget, leaving intermediate schools with no teachers for technology and some schools effectively losing up to seven teachers as rolls grow over the next four years.
"Making a blanket promise that no school will lose more than two teachers, whether they've got 20 or 2500 pupils, is stupid policy and shows how badly the Government is scrambling to recover from this disaster.''
Labour education spokesman Nanaia Mahuta accused the Government of an about-face over changes to class size.
"The moves by the National Government to cover-up an epic blunder around teacher-pupil ratios shows how ill-conceived the entire process was,'' she said.
NZEI National President Ian Leckie said the policy of increasing class size should be reversed.
"Does the Government really believe it can paper over a policy as wrong as this by announcing that the maximum teacher loss in any school will be two?
"Given the strength of parent concern it is also very concerning that the ministry continues to use misleading information to justify its bigger class size policy.''
Mr Leckie said the Prime Minister was wrong when he showed there had been a large increase in the number of teachers employed in the past decade and that student achievement has plateaued and declined.
He said teacher numbers had increased in primary schools in the past decade because of the introduction of 1:15 ratios in new entrant classes and classroom release times for planning and assessment _ both moves to increase the quality of teaching and learning.
"This is the first time in living memory that any government has moved to increase class sizes in our schools. It is vital that it reconsiders this poor policy advice before it is too late to reverse the damage to our public education system.''