KITCHENER -- Ontario Catholic teachers were out of the classroom and on the picket lines across the province.

In Waterloo Region, about 40,000 students were out of school Tuesday as the Waterloo Catholic School Board closed its doors.

Hundreds of local teachers were out picketing at St. Mary's High School, the region's largest Catholic school, as well as four other schools and MPP offices.

Teachers at St. Mary's walked out at 7:45 a.m.

Catholic teachers say they're fighting key issues similar to what public elementary and high school unions are battling.

"We're not here about money, we're here about our education system, we're here about the kids," said one picketing teacher.

"Anyone who says differently has got it wrong."

Other teachers also pointed to new e-learning rules as reasons for the strike.

While the education minister says the dispute is about wage hikes, teachers say that's not the case.

"On the major issues that they contend are priorities, we've either made moves, we've protected our classroom sizes, or we've added new investments," Stephen Lecce said at a press conference on Tuesday afternoon.

It's not just Catholic school teachers that picketed on Tuesday: some public school boards, like the one in Toronto, picketed as rotating strikes continued for the public school board, too.