School boards across Toronto and its suburbs say they will close their schools on Monday if a proposed strike by CUPE education workers goes ahead because they wouldn't be able to ensure student safety.

"We cannot guarantee that our learning environments will remain safe and clean for all students," said the Toronto District School Board in a letter to parents.

Negotiations between CUPE and the province are set to resume Friday afternoon. For the latest on what the two sides are saying about the talks, click here.

"This is not a decision that we made lightly, and we have explored every possible contingency plan to keep schools open."

The TDSB is Canada's largest school board, serving roughly 246,000 students at 582 schools. Toronto's other major board, the Toronto Catholic District School Board, also announced Thursday it too would close "to ensure the health and safety of our students and staff."

The TCDSB has an enrollment of approximately 90,800 students.

CUPE represents about 55,000 education workers across 63 Ontario school boards, including clerical staff, custodians, educational assistants and early childhood educators. They have been on a work-to-rule campaign since Monday.

Neighbouring boards raised concerns

Thursday's announcement by the Toronto-area school boards came after several neighbouring boards voiced similar safety concerns in the event that education workers walk off the job on Monday.

"Please do not send your child to school," said the Peel District School Board in a Thursday statement.

The York Region District School Board announced its plans to close as well.

The Dufferin-Peel Catholic District School Board also sent a letter to parents Thursday, saying it plans to close Monday if a strike proceeds "out of an abundance of caution for the health, safety and well-being of students."

The York Catholic District School Board announced Thursday it, too, would close.

The Peel board serves more than 154,000 students at over 253 schools in Mississauga, Brampton and other communities west of Toronto.

The York board, which serves more than 126,000 students across 213 schools north of the city, said it has "no capacity to cover the skilled work" of its education workers.

Peel board spokesperson Carla Pereira said schools would not be able to perform basic safety procedures, such as checking fire alarms, checking school grounds or answering the phones, if police were to initiate a lockdown.

CUPE workers are already making signs ahead of the potential strike. (@joetigani/Twitter)

"We just do not feel comfortable having children in our buildings without all those safety protocols in place," Pereira said.

"We understand that there is frustration among families at this time, and we ask them for their patience and understanding."

Shortly after Peel's announcement, the board that represents Peterborough, Victoria, Northumberland and Clarington schools also announced it would be closing Monday in the event of a strike.

Boards in Windsor, Ottawa and Waterloo have already announced closure plans, contingent on a walkout.

Work-to-rule campaign caused problems

Some parents and teachers have said CUPE's work-to-rule campaign created unsafe and dirty conditions inside schools.

"They should not be opening the school for the kids on Monday," said a teacher at the York board. CBC is not naming the teacher because she is not authorized to speak about job action.

Another teacher at the Toronto school board said her students have been forced to eat their lunches on hallway floors, which were not being cleaned due to a lack of supervisors.

At least one group of Toronto parents had previously called on the board to close schools if the strike goes ahead as planned. (Farrah Merali/CBC)

"There's a Pop-Tart that's been there since Monday in the hallway outside that's just crushed," she said. More concerning, she said, is young children are running past puddles of water underneath drinking fountains.

"I don't believe there's any way the children will be safe in an open school without CUPE education workers in the building," said parent Sarah Donnelly, who called on boards to close if there's a strike.

The sides have agreed to resume bargaining on Friday in hopes of getting a deal to avoid a full-scale work stoppage.

The Peel board said it may be able to open its schools on Monday if a deal is reached early during this weekend's planned bargaining session.

The government and school boards have said high rates of worker absenteeism remain unresolved while the union has said the impact of government cuts on workers must be addressed.

A spokesperson for Education Minister Stephen Lecce said the government is ready to continue the contract talks.

"We will be at the bargaining table all weekend to endeavour to get a deal that keeps students in the classroom," Alexandra Adamo said in a statement.