TORONTO -- The first update of Ontario's sex-education curriculum since 1998 will bring it in line with other provinces, but could lead the way in teaching the concept of consent, Education Minister Liz Sandals said Monday.

"I think that on having a very explicit conversation about consent -- what does consent mean and what do healthy relationships look like -- I think in that piece we may become the leader," Sandals told reporters.

Many of the concepts in the revised curriculum were already in place, and will now be taught at lower grade levels, but the old policy was badly out of date, she added.

"Smartphones, Snapchat and sexting were not familiar to anyone, let alone students," said Sandals.

Grade 1 students will learn the proper names for body parts and how to understand non-verbal signals like facial expressions and tone of voice.

Sandals said she was surprised that policy quickly came under fire because it's not new, it helps kids clearly communicate in case they get sick or abused, and she doesn't think parents will pull children out of class because of it.

"Given that we haven't had hoards of people withdrawing from the public education system given what's already in the curriculum, to be perfectly honest, I don't anticipate that affect now," said Sandals.

Students in Grade 2 will learn about the stages of development and related bodily changes along with the concept that "no means no," as well as some elements of verbal and physical violence.

By Grade 3, students will learn about same-sex relationships, which Kathleen Wynne, the first openly gay premier, said would help kids with two moms or two dads feel their families are just like everyone else's.

"It's not about explicit information except that it needs to be about kids feeling safe, feeling protected, feeling like they belong," Wynne said.

One change in the new curriculum will be lessons about puberty will move from Grade 5 to Grade 4.

"We dropped it a grade because what we've seen from public health data is that the age of puberty has been constantly dropping," said Sandals. "I can't do anything about that. That's just the way it is."

Students in Grade 6 will learn about masturbation and "gender expression," while kids in Grades 7 and 8 will discuss contraception, anal and oral sex, preventing pregnancy and sexually transmitted infections.

The Liberal government backed away from an attempted update of the sex-ed curriculum in 2010 after protests by some religious groups, but Sandals insisted the update will be in place for the start of classes in September.

She also said Roman Catholic educators were consulted and must follow the curriculum in private schools as well as the public system.

The Progressive Conservatives complained the government did not consult enough parents before introducing the revised sex-ed curriculum.

Chris Markham, executive director of Ontario Physical and Health Education Association, called the curriculum update long overdue and cautioned critics about overreacting.

"I think the Opposition and everyone in the public and the media especially need to understand the content of the curriculum before we start forming opinions, before we start fearmongering and putting out statements that are completely incorrect," he said.