Some Calgary parents say they are being forced to pay for private tutors to pick up where overworked teachers are leaving off.  

Valerie Noel's 15-year-old twin daughters are usually straight-A students.  

But with more than 30 students in their math class last year, the girls weren't getting the help they needed, Noel said.

"We found when they were coming home with homework they didn't know what they were doing," she said.  

With the girls facing the prospect of getting Cs, Noel hired a tutor. She said it’s a step parents shouldn't have to take.

"Our school system is failing us in that way. That what we're expecting and what they should be learning to carry them through life isn't happening and we have to go outside of that," she said.

Louise Ridout said her business, EducationWise Tutoring, is growing by 10 per cent a year.

"Their teachers just don't have as much time as they had for them before and that's concerning both to the students and to their parents," she said.

According to Calgary public teachers, this year's budget shortfall could push some high school class sizes up to 40 students.

And that means more parents like Noel could end up paying out of pocket to keep their children on track.

"It’s not right, because the kids that will get the extra help will have the advantage at the end of the day," she said.

"They're going to get the spots at university, whereas everybody should have that door open for them."