TORONTO -- Ontario schools resume this week in a more stable state than when they closed in June amid the threat of massive teachers' strikes, but it will not be entirely problem-free with work-to-rule campaigns and controversy over a new sex-education curriculum lingering.

Over the summer the Liberal government was able to negotiate contracts with high school teachers and English Catholic teachers, but deals with the Elementary Teachers' Federation of Ontario, Francophone teachers and education workers are still outstanding.

Elementary teachers will not be planning fundraising activities or field trips or attending open houses after regular school hours. The union is calling the administrative strike Phase 2 of its work-to-rule campaign they started in the spring.

But where talks broke down several times in the spring, the parties are now back at the bargaining table. The Education Ministry said progress has been made and talks continue Tuesday.

The Canadian Union of Public Employees said the support staff it represents across all boards will be staging their own work-to-rule campaign. Staff won't be working through their lunches, taking work home or attending unpaid meetings, CUPE said. But they too have bargaining dates with the government -- five so far over the next two weeks -- and hope in that time they can reach a deal.

The last school year wrapped amid talk of all major teachers' unions being on some form of strike in the fall, but deals were recently reached with the Ontario Secondary School Teachers' Federation and the Ontario's English Catholic Teachers Association.

Where tensions don't seem to have eased is among parents upset by a new sex-education curriculum being implemented in schools this year.

Feras Marish, with Parents Against Ontario's Sex-Ed Curriculum, said over the summer parents belonging to his group have become more informed on the "dangers" of the curriculum.

"It started by being emotional, parents worried about their kids because the topic itself is taboo and it's known to be dangerous," he said.

Now he said the group wants to debate the government on the scientific merits of the curriculum, saying the curriculum forces children to make sexual decisions before they are capable.

"We are 100 per cent sure if they agree to it...they are going to be exposed," he said.

In at least one school board, the sexual education lessons will not be taught until next spring. That's in part to allow for the elementary teachers' labour strife to be resolved, as their work-to-rule involves not participating in ministry-directed training, such as on the new curriculum, but also to allow for more communication with parents, said Jeff deFreitas with the Peel District School Board.

"Not to belittle the conversation, but the actual components of the curriculum that people are concerned about are such a small part of a very large curriculum document," he said.

Marish likened it to "a drop of poison in a cup of water."

"That drop of poison will still kill you even if 99 per cent is just pure water," he said. "That part of the curriculum is very poisonous, is very dangerous."

Some parents have threatened to pull their kids from school over the curriculum, and Marish said home schooling is being encouraged among his group.

But at a Toronto school that saw a more than 90-per-cent absentee rate on a day parents kept their kids home to protest the curriculum, the superintendent has not received any more home schooling requests than she has in previous years, said a spokesman for the Toronto District School Board.

Education Minister Liz Sandals has staunchly defended the curriculum, saying it was last updated in 1998, "long before Facebook and Snapchat became part of everyday life" and now it gives kids information that can help keep them safe and healthy.

Under the changes, Grade 3 students will learn about same-sex relationships, kids in Grades 4 and up will learn more about the dangers of online bullying, while the perils of sexting will come in Grade 7.

Lessons about puberty will move from Grade 5 to Grade 4, while masturbation and "gender expression" are mentioned in the Grade 6 curriculum. Anal sex is part of the Grade 7 curriculum, in the context of choosing to abstain from or delay certain activities in order to avoid sexually transmitted infections.