A popular math teacher at Wantagh High School was arrested Wednesday evening for having sex with a 16-year-old student, police said Thursday.

Heather Kennedy, 25, who has taught math at Wantagh High School for three years, was released on $35,000 bond after she was arraigned in Nassau County First District Court in Hempstead on charges of rape and endangering the welfare of a child.

According to Nassau Detective Lt. Richard Zito, Kennedy had sex with the boy in his car last week in the parking lot of another area high school, the New York Post reported. The one-night stand was discovered the next morning after the student’s father grilled him about coming home late. The boy, whose name has not been released because he is a minor, said he was with friends initially, but later came clean about the alleged encounter with the teacher, Zito said.

“We believe it was a one-time incident,” Zito said. In fact, the teacher had a good reputation with students and administrators alike. She was “well thought of by school administrators,” Zito said.

“I’ve known Heather for a long time and it’s certainly out of character for her to be accused of such a crime,” said Kennedy’s lawyer, Steven Zimmer, according to the New York Daily News.

Meanwhile, “the teacher has been immediately administratively reassigned out of the classroom to her home, pending the outcome of the investigation,” said school representative Debbie Shor-Casper.