TORONTO -- Ontario is open to negotiating a smaller boost to class sizes, the education minister said Thursday, while downplaying impacts of those larger classes -- messaging that teachers decried as an "insult" and a "sleight of hand."

The government had announced in the spring that high school class sizes would rise from an average of 22 to 28 students over four years.

Education Minister Stephen Lecce said Thursday that he is willing to consider ways to bring that 28-student average down, while still keeping cost savings top of mind.

"My message to unions then and today and any trustees' association (is) if they can bring forth ideas within our fiscal authorities, if they bring forward innovative ideas that can reduce our class numbers, I am ... open to those ideas," he said.

Contracts for teachers and education workers in the province expire on Aug. 31, but bargaining for a new deal is still in its early stages.

The Ontario Secondary School Teachers' Federation was at the Ontario Labour Relations Board on Thursday to determine what issues should be bargained centrally, and what should be deal with at local tables.

The talks are expected to be difficult, given the move to larger class sizes, which the government has said will mean 3,475 fewer teachers in the system. The Progressive Conservative government has said that will be through not filling positions when teachers quit or retire, saying there will be no "involuntary" job losses.

Teachers have warned that the changes will lead to fewer course offerings and extracurricular activities, and that some classes, specialized ones, in particular, would balloon in size.

Lecce said Thursday that he wanted to clarify "misinformation" that was spreading about class-size increases, saying that for this school year they would only rise to an average of 22.5.

"We have said in our plan from the spring that this September, classrooms would be regulated at 22.5 -- that's 22 plus attrition," Lecce said. "We always said that."

There are no references to a 22.5 average for this school year in the materials from the former education minister's original announcement.

OSSTF president Harvey Bischof said Lecce's announcement is smoke and mirrors, since the government's plan is still to increase class averages to 28 over time.

"This is nothing more than a feeble attempt at sleight of hand on the part of Minister Lecce," he said in a statement.

The Ontario English Catholic Teachers Association said school boards have already been planning with the 28-average goal in mind, resulting in courses and programs being cancelled.

"The announcement today by Minister of Education Stephen Lecce is an insult to students, families, teachers, education workers and all Ontarians," president Liz Stuart said in a statement.

"If the government was planning a different course of action, they could have told Ontarians about it months ago. Instead, they have been content to allow chaos and confusion to unfold."