It means 24,000 students in the Durham school district will be staying home.
The two sides say no talks are scheduled and the school board issued a statement that it had no choice but to close schools on Monday out of concern for student safety.
The district includes Ajax, Whitby, Pickering and Oshawa.
School board chairman Michael Barrett issued a statement on Saturday expressing disappointment that the teachers have opted for "the picket line rather than the negotiations table."
The Ontario Secondary School Teachers Federation issued its own statement, accusing the school board of "punitive micro-management of teachers' professional lives."
"This employer's refusal to engage in real negotiations has really left us no option," said Dave Barrowclough, president of the teachers local in the district.
"They refuse to enshrine in the collective agreement even language that would clearly enable us to improve our teaching practices."
It's the first round of negotiations since the province brought in a new bargaining system, with both local and provincial talks.
The high school teachers' union announced Wednesday that it had walked away from the provincial talks, which Education Minister Liz Sandals said probably increased the likelihood of a strike in Durham.
But Sandals suggested it was a bargaining tactic by the powerful teachers' union and predicted they would eventually return to try to reach a new deal.
The government faces more disruption on provincial schools as the Elementary Teachers' Federation of Ontario, which applied for conciliation in late March, asked for a "no board report" Monday, signalling that talks with the province are at an impasse.
The union would be in a legal strike position 17 days after the report is issued.
"The government and (the Ontario Public School Boards' Association) appear intent on eroding our existing rights and taking us back to the bad old Mike Harris days," the union said in a statement, referring to the former Tory premier whose relations with the unions deteriorated in the '90s.
"They do not appear to be serious about finding a reasonable way to resolve this collective agreement which has been expired now for eight months. Instead, they are provoking a crisis."
It's been three years since the Liberals forced contracts and wage freezes on the teachers through legislation, angering the unions, and the relationship has since slowly improved.
However, as the Liberals try to eliminate a $10.9-billion deficit through measures that include "net zero" increases in contract negotiations, dissent appears to be brewing — although the teachers say wages are not the only issue.