The judge called Warren Fertig's actions — quote — "morally despicable" and gave him five years in prison.
The 73-year-old was charged in September 2011 after a woman went to police saying she had sex with Fertig over a three-year period starting when she was 12 and Fertig was a teacher at Riverglen School in the 1970s.
An agreed statement of facts showed the girl also babysat Fertig's children during that time.
The Crown had been seeking a prison term between two and four years while the defence wanted a conditional sentence.
The victim says she feels better about herself and is satisfied with the sentence.
"I think it's fair ... it's important that people are penalized for their actions and it's a crime against a child and it severely affects their life and it has to stop," she said outside court on Friday.