Ontario's elementary school teachers say they're acting within the law by waiting until Friday to tell parents whether there will be a full strike next week — and the education minister wants to look at changing the rules.

The Elementary Teachers' Federation of Ontario is planning a province-wide strike starting next week, but is refusing to confirm if that will be a complete withdrawal of services, which would close schools, or an administrative work-to-rule.

The Liberal government brought in legislation last year that separated bargaining into local and central talks, and also said employees must give five days' notice before striking.

Following the letter of the law, the ETFO provided notice Tuesday that some sort of strike will take place Monday, but Education Minister Liz Sandals urged the union to announce its plans as soon as possible, saying parents need to make alternate arrangements.

Sandals said she will "certainly" consider amending the legislation, during a planned review of the bill once the bargaining is finished, to specify that unions must divulge the type of strike they're planning.

"We'll have to see whether we're legally able to do this," Sandals said. "If it's possible to tighten that up, especially when you've got really small children...boards will figure out how to manage it, but we shouldn't put parents through this uncertainty."

Friday news conference

The union has told members they will be on a work-to-rule campaign next week, which means they'll refuse to administer standardized tests and prepare report cards. But union president Sam Hammond isn't confirming until a news conference Friday.

"ETFO has fulfilled its legal obligation to provide notice of legal strike action," he said Thursday in a statement.

"We do not take strike action lightly and have been pushed into such action as a result of unrealistic and concession bargaining demands tabled by the Liberal government and the Ontario Public School Board Association."

The union said the government wants to remove class-size language from collective agreements and direct how teachers spent their preparation time.

Progressive Conservative education critic Garfield Dunlop said the Liberals' school board bargaining law has "resolved absolutely nothing."

NDP Leader Andrea Horwath said "the more clarity the better," though she said the union did give parents a "head's up."

"I think any parent with a small child in school right now who isn't aware that there's a possibility that on Monday school will not be functioning because there will be a picket line out front, they haven't been paying very much attention to what's happening with the crisis in education that the Liberals have caused."

The elementary teachers' strike comes as more than 70,000 high school students in the province sit home because teachers in the Toronto-area boards of Peel and Durham as well as in the Sudbury area have walked out.

Talks are set to resume Friday between the Ontario Secondary School Teachers' Federation and the Durham school board, where 24,000 students have been out of school since April 20.

The OSSTF has said central talks with the province are at an impasse.