Erica Ann Ginnetti, a former Lower Moreland High School teacher, pleaded guilty Tuesday to institutional sexual assault and disseminating sexually explicit materials to a minor after admitting to having sex in 2013 with a 17-year-old student in her car.

The math teacher faces a maximum of seven to 14 years in prison. She is free on bail awaiting sentencing.

The investigation started following a tip that students were overheard discussing the teacher's relationship with the student. Ginnetti, now 34, approached the student at a school dance in May and began flirting with him, police said.

Within weeks, they were communicating daily, and Ginnetti, who is married and has children, began sending him sexually charged text messages, photos, and videos of herself, police said.

Investigators retrieved copies of the messages, photos, and videos from the student's cellphone.

Sophia Polites, a Montgomery County assistant district attorney, said, "Those pictures depicted her in an undressed fashion - wearing a bikini, wearing a thong in another image."

In July 2013, Ginnetti and the student met at a Starbucks store in Northeast Philadelphia, then went to an industrial park along the border of Philadelphia and Lower Moreland and had sex, police said.

Afterward, the teacher allegedly told the student not to tell anyone about the encounter.

Polites said she was unsure when Ginnetti will be sentenced, and until then she cannot say much about the case.

Ginnetti was fired from her teaching position at Lower Moreland in January following her arrest. She had worked there since 2007.

Marc Neff, who represented Ginnetti at Tuesday's hearing in Montgomery County Court, said Ginnetti has admitted her culpability, and he plans to let the judge know the good things she did during her teaching career.

"She wants to put this behind her and get back to her family," Neff said.