Now an 18-year-old university student, the witness told Justice John McMahon that he kissed, petted and fondled the 40-year-old married woman while babysitting her two young children during a two-month relationship that ended in January 2010.

The then 15-year-old boy, who cannot be legally identified, would play hide-and-seek with her two children upstairs while her husband was out, sometimes playing hockey. Meanwhile, he and Gowans made out in her basement, he told the judge-alone trial.

His first sexual encounter came in November 2009, court heard. Gowans steered him to the basement couch where she straddled him. She unzipped and lifted her sweater, revealing her bare breasts, the teen recalled.

A few months earlier, Gowans paid off a bet -- made through text exchanges -- to reveal her cleavage to him after he defeated her in a 2009 waterfront race. The teen admitted he had a crush on Gowans since Grade 8 when she taught him French at Joseph Howe Sr. Public School in the city's east end.

After graduating in 2008, the teen maintained close contact with Gowans -- seeing her three to four times a week -- by babysitting and mentoring her children and running alone with Gowans.

But nothing sexual transpired between them, he said, until he attended Grade 10 at Mowat Collegiate in the fall of 2009.

The teen's relationship ended he revealed his involvement with Gowans to his mother. He reported it to police in January 2010.

There were no incidents of intercourse, court heard.

Gowans, now 42, and a popular teacher until her resignation after she was charged, has pleaded not guilty to sexual assault, sexual exploitation and sexual interference.

Defence lawyer Peter Brauti is denying that any sexual activity occurred except once when the teen made a sexual advance on her. She rebuffed him and cut off any contact with him in January 2010.

The trial continues Wednesday.