The Ford government has announced that class size caps for grades 9 to 12 will increase from 22 to 28 students.
Education Minister Lisa Thompson said Grades 4 to 8 will also see an increased class size.
Kindergarten and grades 1 to 3 class sizes will stay the same.
The Ontario government says gender identity and consent will be taught as part of a new sexual-education curriculum that will be introduced to schools by the fall.
The province has released the broad lines of the new sex-ed curriculum in an announcement that also lays out its plans for other aspects of the education sector, including teacher hiring.
The curriculum will replace an interim teaching plan based on 1998 materials that was put in place last year after the Progressive Conservatives repealed a 2015 curriculum from the previous Liberal government.
The 2015 curriculum addressed consent, online bullying, sexting, same-sex relationships and gender identity.
The province previously held an online consultation on the issue and an overwhelming majority of those who weighed in through that forum in the first day opposed the decision to scrap the 2015 curriculum.
The province says parents will still be able to opt out of having their kids exposed to certain topics in the sex-ed class, and the ministry will issue online modules for those who want guidance on discussing those topics at home.
The full curriculum is expected to be released in May and implemented in September.
"Our plan ... was about improving curriculum, modernizing the learning opportunities that teachers and students have to embrace, as well as making sure we have the best talent in the classrooms," Thompson told Kitchener Today with Brian Bourke on 570 NEWS.
"In terms of increasing our class sizes in high school, we feel that our students will have a broader base to work ... we'll make sure that we have the best teachers in the classroom. Math teachers, should be teaching math ... or French teachers, teaching French." she added.
Thompson says the research they've looked at demonstrates the biggest factor in determining student success is the effectiveness of the teacher.
Watch the complete announcement below:
#BREAKING - The Ford government announces that class size caps for grades 9 to 12 will go up from 22 to 28 students. Grades 4 to 8 will also see an increase. Kindergarten and grades 1-3 class sizes will stay the same.— Richard Southern (@richard680news) March 15, 2019