A teacher accused of sexual exploitation was part of a BlackBerry Messenger group that badmouthed students at her Cambridge school, a former student testified Thursday.

Jacqueline Lavigne is charged with sexual exploitation in connection with an alleged sexual encounter between her and a then-17-year-old student in 2011.

She has pleaded not guilty.

Thursday’s testimony came from two other former students of hers at Monsignor Doyle Catholic Secondary School.

One told the court that Lavigne was part of a BBM chat group that also contained him, another student and the complainant in the case – the student she is accused of having sex with.

Conversations in the group were initially school-related, he said, but the students eventually began badmouthing some of their peers, with Lavigne joining in.

Also included in his testimony was his recollection of personal BBM conversations between him and Lavigne – including one where the teacher allegedly told him she was drinking and by herself.

Monsignor Doyle principal Christopher Woodcroft also took the stand Thursday, telling court that he interviewed Lavigne and multiple students after being notified about the allegations and took the matter to executives at the Waterloo Catholic District School Board, who told him to contact police.

The second student to take the stand Thursday testified that Lavigne once told her the complainant was staring at her breasts, and repeatedly suggested he shouldn’t be with his girlfriend of the time.

Before Lavigne’s arrest, Woodcroft said, school policy required any direct email contact between teachers and students to include another staff member.

That policy has since expanded to cover BBM chat and all other forms of electronic communication.