Thousands of Ontario teachers rallied outside the provincial legislature today as the province's Labour Relations Board considers whether strikes by high school teachers in three boards should be declared illegal.

Holding up signs and union flags, teachers chanted their support for their striking colleagues in Durham Region, Rainbow District, which includes the Sudbury area, and Peel Region.

James Clyke, president of the Rainbow District local, says the relationship between members and the boards is currently "not very good" and he's not sure how mandating teachers back to work will affect that.

Others describe feeling "very disheartened" at the tone of discussions with the province.

Mary Karchemny, an elementary school occasional teacher in Waterloo Region, says Premier Kathleen Wynne is going back on her promise not to strip teachers' collective agreements.

Striking teachers could find out as early as this afternoon whether they will be sent back to the classroom.

More than 70,000 students have been out of class for weeks and the three school boards say the strikes are unlawful.

The boards believe the Ontario Secondary School Teachers' Federation is staging local strikes on central issues, which is not allowed under a new bargaining system the Liberal government introduced last year.

It separates local and central negotiating, with issues such as money and class sizes being discussed at the provincial table.

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.

Education Minister Liz Sandals says if the Ontario Labour Relations Board decides the strikes are illegal it's also up to the boards to provide direction on any next steps.

"The most important thing to understand is the fact that the OLRB is looking at the issue of three specific local strikes doesn't prevent us from negotiating at the central table," she said.

However, no central negotiations are taking place with either the high school teachers or the elementary teachers, who are staging a work-to-rule strike. Both sets of talks are at an impasse but Sandals said the ministry is working to get everyone back to the central tables. Secondary school support staff negotiations did take place Wednesday, she said.

Sandals says the ministry wants to make arguments at the hearing because it has a legal interest in issues related to the structure and purpose of the School Board Collective Bargaining Act.