That's after the Ontario Labour Relations Board ruled the job actions illegal Tuesday evening as the legislature debated back-to-work legislation.
Education Minister Liz Sandals says lawyers are looking through the ruling, but in the meantime the Liberal government will still try to get the legislation passed.
The labour relations board ordered a two-week moratorium on the strikes but the back-to-work legislation bans strikes in those boards for the rest of the school year.
Labour board chair Bernard Fishbein sided with the school boards in concluding the three local strikes were, at least in part, on the central issue of class sizes.
This is the first round of negotiations to formally separate local and central bargaining under legislation the Liberal government brought in last year.
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, and Fishbein agreed.
ALSO ON HUFFPOST: