HAMILTON -- Premier Kathleen Wynne says that once this "difficult" round of negotiations with teachers is over, she's open to making changes to the process.

The Liberal government introduced back-to-work legislation Monday for high school teachers on strike in the regions of Peel, Durham and the Sudbury-area Rainbow District.

They had hoped to get it passed in just one day with unanimous consent of all parties, but the NDP did not agree, so it will go to second reading debate after 3 p.m. today.

It comes as there are rumblings of a potential provincewide high school teachers' strike in the fall, following an application for conciliation by the Ontario Secondary School Teachers' Federation, and elementary teachers are on a work-to-rule campaign.

This is the first round of negotiations to formally separate local and central bargaining under legislation the Liberal government brought in last year.

While Wynne says it was necessary to have a process like that, she would consider looking at changes.

"Right now we're in a difficult negotiation because we're operating in a net zero environment where there isn't new money for compensation and at the same time we are using this new process," she said Tuesday in Hamilton.

"If there are changes we need to make to the process once we're through this, then we can look at that."

The Ontario Labour Relations Board is considering an application from the Durham, Rainbow and Peel school boards on the legality of the strikes. While the decision will come too late to be of any effect in the three local strikes -- with back-to-work legislation already going through -- Education Minister Liz Sandals has said the ruling will still be of interest during a planned review of the new School Boards' Collective Bargaining Act.

The legislation was intended to bring clarity to labour negotiations, but it came under fire at the labour board as not clear enough in some areas.

Lawyers for the three school boards argued that although the law doesn't explicitly ban teachers from staging local strikes on provincial issues, that's what it was meant to do. The school boards claim the teachers and their union have been largely protesting about class sizes, which is a central issue, and in the boards' opinion, the act prevents local strikes on central issues.

Sandals has also said she would "certainly" consider, during the planned review of the legislation, amending it to specify that unions must divulge the type of strike they're planning.

Following the letter of the law, the Elementary Teachers' Federation of Ontario provided more than five days' notice before their work-to-rule campaign that began Monday, May 11, but refused until the following Friday at 2 p.m. to say it would be an administrative strike, with parents worried for days that there would be a full withdrawal of services.