TORONTO -- Conservative groups are fuelling the vocal opposition to Ontario's new sex-education curriculum, Liberal Education Minister Liz Sandals said Tuesday as thousands of people protested outside the legislature.

The protesters' ranks swelled from a couple hundred at a similar rally in February to several thousand on Tuesday. In that time, said Sandals, the opposition to the sex-ed curriculum has become overwhelmingly Conservative.

"The correspondence that I received initially on this issue was very much parents who might have been misinformed about the details of the curriculum, but who were genuinely concerned," she said.

"I also got a lot of extraordinarily offensive homophobic correspondence, which I would not repeat in public. But the last week or two, the correspondence I've been receiving from some of the groups that are out there organizing the protest have turned into, 'We have to fight the Liberal curriculum because the Liberals didn't consult with Conservative groups."'

After the first protest, Premier Kathleen Wynne, who is openly gay, said some of the opposition was motivated by homophobia.

The sex-ed curriculum was last updated in 1998, before smartphones were ubiquitous or sexting had been invented.

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 dangers 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.

Parents were not consulted enough before the curriculum was set in stone, protesters said, arguing that it's a parent's right to educate their children about sex. Their concerns about the curriculum ranged from material that was being taught too early to saying children should not be taught about same-sex relationships and different gender identities.

"I will be the first one to pull them out of the class because it's not fair for my religion and it's not fair for my child to be confused," said Amina Yonis, a mother of seven. The curriculum, particularly mentions of same-sex marriage, conflicts with her Muslim faith, she said.

"This is ridiculous what they want to teach our kids and poison their minds and we don't accept this."

Rose Nadeau, a grandmother, said she too disagreed with teaching same-sex marriage in the curriculum because it goes against Catholicism.

"I think the parents should teach them what's right and wrong and not the teachers at the school, or the principals, or the government," said Nadeau.

"I don't believe in teaching children about different ways of having sex and about masturbation and all of that. That's something that a child is going to learn on their own despite what anybody teaches them anyway."

Progressive Conservative MPPs Monte McNaughton, who dropped out of the PC leadership race last week, and Jack MacLaren spoke at the protest, calling on the government to back down from its firm deadline of having the curriculum in place in September, and waiting to consult more with parents.

The government says school council chairs at all 4,000 schools across the province were consulted.

"What I see on the lawn is a bunch of Conservative leadership candidates, and I don't think this is actually where the existing caucus wants to take this," said Sandals.

Neither of the Progressive Conservative leadership candidates Patrick Brown and Christine Elliott attended the rally, though Brown was listed as a "tentative" speaker. Elliott has said parents were not consulted enough.

The president of Canada Christian College, Charles McVety -- one of the most vocal opponents to the new curriculum -- has described it as a "radical" educational experiment, focusing on references in the curriculum to six gender identities -- male, female, transgender, transexual, two-spirited and intersex.

Sandals said a lot of people are confusing terminology in this debate, stemming partly from McVety.

"Mixed in with the Liberal curriculum is the accusation that we're turning two genders into six genders, so I now know where it came from -- Mr. McVety," she said.

Protesters called on Wynne to face them, but the premier was attending a climate change meeting in Quebec.

Asked if she would address the protesters, Sandals said, "If I were to walk into a crowd of 3,000 people the OPP security people would flip out."