The government says it is in the final stages of a plan to build more school classrooms more efficiently.
The Ministry of Education has had to pause 20 big projects to deliver over 100 classrooms amid cost over-runs and roll growth uncertainty.
The minister, Erica Stanford told Nine to Noon the ministry had been over-promising and under-delivering.
"I mean it was a massive shock, to be honest with you, to come in last year to find out that there's a whole list of schools who have had their expectations raised, who have been going through processes for years, to find out literally a week before things start, that it's not going ahead," Stanford said.
The bad experience of a delayed innovation centre at Kaipara College had exposed the delivery problems and inadequate communications by the ministry, she said.
Asked if she had signed off on the mass pause on projects by the ministry she replied: "This is purely operational, I'm not signing off on anything to do with school property.
"I think the journalists and me are going through the same process of, 'How on earth has this happened?'
"We've got huge pipelines of expectations that have been raised, and an inability to deliver on that, teamed with poor communication to the sector."
Ashburton College has 22 new classrooms, but the building of 30 more has been put on hold.
Principal Simon Coleman said the ministry had not told them what happens next - that the minister's summation of under-delivery and poor communication summed up their experience.
"That's probably the biggest thing for us, is just having some clarity ... and be realistic about what we're getting, I guess not over-promising ... that would make a massive difference for us."
They had got stages one and two built, which was great, Coleman added.
It was not just rising construction costs or the severe weather damage last year causing disruptions, Stanford told RNZ.
A lot was also spent on "fancy architects" and bespoke classrooms, she said.
"Then the costs blow out and we turn around and go to the school 'oh gosh, we're really sorry - three years down the track after all this planning work you've done, but we now have to rescope because it's massively over budget'."
"We are working on a plan at the moment to make sure we are building cost-effective classrooms, so that actually we can build more classrooms, rather than very expensive blocks at the expense of other schools.
"Over the last six years, we haven't been doing that."
She would announce details of the plan in coming weeks, Stanford said.
"We are just going through the final stages of planning around this."
Coleman, who is new to the job, said Ashburton had had a rush of a hundred extra students to start the year, so the roll - at 1330 - already exceeded what the paused project was designed for.
It was difficult for the students, dealing with half the school that had leaky classrooms, and grounds split up by construction safety fencing.
"Once the contractors have gone, which I believe will be the end of this term, then obviously we will be waiting ... for what happens with the next stage."
Stages one and two appeared to have swallowed most of the entire $60m budget, leaving none for stage three (30 classrooms, a library and staffroom), Coleman said.
It was the first he knew today, that the minister was intervening and had a plan.
"Now that we're hearing this information about what Minister Stanford is doing, we will definitely be making contact with her and ministry people, so that we can actually find out where are we with this, so we know what the plan is for Ashburton College."
Stanford specified the plan was to improve how projects ran, but did not say if it stretched to telling the 20 'paused' schools what would happen now.
The ministry has had a modular building programme, and offsite classroom construction option, for years.
For instance, a 2021 ministry publication outlined five types of "reference" designs for single- and two-storey blocks.
"Reference designs are easily repeatable school designs," it said.
Several schools have told RNZ the ministry has been getting better in recent years at getting projects done and communicating about them.