For several months this year, Katherine Korakakis' kids had substitute instructors that were "not qualified to teach the subject," said the Montreal parent, whose province started this school year thousands of teachers short.

"It wasn't a math teacher who was teaching math. It wasn't a French teacher who was teaching French."

She was already worried about learning loss after the pandemic, and scrambled to get her teens extra tutoring, a luxury she knows not everyone can afford. 

"Having a child sc…