Students across Ontario walked out of class on Friday to protest the provincial government's decision to repeal a modernized version of the sex-ed curriculum.

The walkouts -- called "We the students do not consent" -- took place in schools from Niagara Falls to Ottawa and saw students gather outdoors, hoist handwritten signs and chant about the need for relevant sexual education.

"Some adults, such as (Premier) Doug Ford, may have grown up in a different time," said Luca Lichner, a 16-year-old who walked out of one Toronto school. "With times changing and everything updating, we should also update our sex education instead of going back in time."

The province's Progressive Conservative government announced in July that it would scrap the modernized sex-ed curriculum brought in by the previous Liberal regime in 2015.

That document included warnings about online bullying and sexting, but opponents, especially social conservatives, objected to parts addressing same-sex relationships, gender identity and masturbation.

Late last month, the government released a curriculum meant to temporarily replace the modernized version. Observers have said it makes passing mention of modern concepts such as the internet and cellphones but largely reverts to the vague language and broad topic outlines used in the previous curriculum last updated in 1998.

Lichner said she worried her younger brothers -- aged five and nine -- may not be taught about issues like sexting and same-sex relationships as thoroughly as they would have been before.

"If they would be growing up under this government, if they are not taught about these issues then I would be greatly concerned for them," she said.

As they protested, Lichner and her peers carried signs emblazoned with slogans like "1998 called: it wants its curriculum back" and sang songs such as Salt-N-Pepa's "Let's Talk About Sex." Others carried rainbow-coloured signs in a nod to the LGBTQ issues critics say aren't properly reflected in the revised curriculum.

"We find it appalling that we don't have a curriculum that is up to date," said Frank Hong, a Grade 12 student who helped organize the rallies. "For some vulnerable teens, these are issues of life or death."

Those sorts of concerns for a younger generation were shared by Indygo Arscott, a 16-year-old who is two-spirit and uses gender neutral pronouns.

"When I was growing up, (the old curriculum) made me feel alienated ... all I learned about was heterosexual relationships or identifying as either a male or a female," Arscott said. "There's a lot of kids that are going to feel alienated."

When asked for comment on the student protests, a spokeswoman for the education minister noted that the province was launching public consultations on a new sex-ed curriculum next week and encouraged people to participate.

Friday's student action also aimed to voice opposition to the cancellation of curriculum writing sessions designed to fulfil findings of the Truth and Reconciliation Commission, a move Arscott described as a step backward.

"It's time that kids in especially the public school system get educated about Indigenous issues and Indigenous history, especially from the perspective of Indigenous people," Arscott said.

The sessions, which were set to take place in July, had been aimed at enhancing Indigenous perspective in the province's curriculum. The government also scrapped curriculum writing sessions on American Sign Language and Indigenous Languages in kindergarten set for the same time as a cost-cutting measure.

At the time, a spokesman for the ministry of education said the government would still work with "experts, elders and Indigenous communities" to develop "support materials" for the updated curriculum, but did not provide any specifics.

The province has said a new sex-ed curriculum is expected for the 2019-2020 school year.