High school teachers in the Toronto-area regions of Peel, Durham and the Sudbury-area Rainbow District are on strikes that have kept more than 70,000 students from class for weeks.
Education Minister Liz Sandals — who has not yet said if the province is considering back-to-work legislation — says the government is concerned the strike could put the school year in those boards in jeopardy.
Meanwhile, high school teachers in Ottawa and Halton Region will begin an administrative strike May 21.
The Ontario Secondary School Teachers' Federation says the local unions for the Ottawa-Carleton and Halton boards will partially withdraw services, which means teachers won't add comments to report cards or attend staff meetings or school board meetings, and will hold some picket lines over the lunch hour.
Regular school operations will continue, as will field trips and extracurricular activities.
"We are increasingly concerned the ongoing local strikes in Durham, Rainbow and Peel district school boards may be putting the school year at risk," Sandals said Friday in a release.
"The best solution is to reach a negotiated agreement and we remain committed to achieving that by working together with all of our partners," she said.
The Ottawa and Halton teachers' partial strike comes as elementary teachers across the province are staging a similar job action, withdrawing from administrative duties but continuing with classes and extracurriculars.
Those three school boards where high school teachers are on strike have asked the Ontario Labour Relations Board to declare them illegal, and the hearing is set to continue into next week.
This is the first round of negotiations under a new bargaining system the Liberal government introduced last year, separating the process into local and central talks. The local high school teachers' unions that are on strike are negotiating with their respective school boards, not the provincial government.
But the school boards believe the OSSTF is staging local strikes on central issues, such as money and class sizes, which is not allowed under the new system.
The local unions deny the school boards' assertion that the local strikes are just part of an overall provincial strategy to put pressure on the government.
Negotiations between the province and the central OSSTF have been at an impasse for weeks.