TORONTO -- Ontario schools are already dealing with escalating strike action by high school teachers, and now a so called parents and students strike could keep even more kids out of classes.

A group of parents is threatening to pull their children out of school this week to protest Ontario's new sex-education curriculum.

A Facebook group called "Parents & Students on strike: one week no school" is encouraging parents who oppose the 2015 sex-ed curriculum to keep their kids at home.

The group also offers a letter template for parents to give to their children's respective schools, which states the curriculum contains "age-inappropriate" content that does not align with the "principles and beliefs" of families.

Toronto District School Board spokeswoman Shari Schwartz-Maltz said it's hard to say how many families will join in the protest. She notes some parents downloaded the letters and handed them in ahead of time, while others have made verbal commitments "so the numbers are next to impossible to know" until midday on Monday.

"Everybody that's not in school will be marked absent and teaching and learning continues. So if you are not present in class, we're following the same policies we do in any other case," said Schwartz-Maltz. "Children/families are responsible for the work missed."

The templated letter states that parents believe it's their responsibility to teach these values to their children, in addition to having complete control over when the topic is first introduced.

"We live in a democracy and people are permitted to protest and voice their opinions and this is clearly the way some parents feel is the best way to express their opinions," Schwartz-Maltz said.

Janet McDougald, chair of the Peel District School Board, said she thinks a "fair number" of parents will pull their kids from school for at least the first day of the week in the culturally diverse region just west of Toronto.

Thousands protested the new sex-ed curriculum on the lawn of the legislature last month and many said they came from Peel Region communities. But McDougald says there is a lot of misinformation being intentionally circulated about the curriculum.

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.

Some opponents of the curriculum say it's not age-appropriate, others insist children should not be taught about same-sex relationships and different gender identities, while still others wrote on the Facebook group that the curriculum is full of "deviant sexual practices" and amounts to "child abuse."

Premier Kathleen Wynne met privately last week with a group of parents who demanded she withdraw the curriculum. She told them the new curriculum will take effect in September as planned.

Even though education is a provincial jurisdiction, Wynne said she has been warned that the curriculum could be used against the federal Liberals in the upcoming election campaign.

"I have been told that this is something that could be used as a wedge issue," she said recently in Ottawa. "I think that we just need to be aware of that and we need to all be armed with the facts."