By Brad Segall and Walt Hunter

LOWER MORELAND, Pa. (CBS) — An honors math teacher at Lower Moreland High School is free on $50,000  unsecured bail, charged with having a sexual relationship with a teenage student at the school.

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Montgomery County prosecutors say Erica Ginnetti, a married, 33-year-old mother from Philadelphia, approached the 17-year-old boy at the prom last year and asked him if he wanted to work out at her gym.

Police say she began sexting the teen —  sending him explicit pictures and messages — escalating to a sexual encounter in a car.

“They were extremely explicit — very detailed, very graphic, and totally inappropriate for a teacher to be communicating in this way with a student,”  Montgomery County DA Risa Ferman told KYW Newsradio today.

Police say they received a report earlier this month from “Child Line” that a teacher was having a sexual relationship with a student.

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“There is a line that you can’t cross and it is your responsibility to make sure that you don’t cross that line,” Ferman said.

“Stunned, speechless, couldn’t even think a thought,” neighbor Jackie Simko said.

She remembers Ginnetti as a caring teacher who helped her with her own education.

“She tutored me while I was in college. It’s mind blowing. You know, to hear something like this,” she said.

Court papers reveal that Ginnetti admitted to the affair.  The school district says she is now on administrative leave and they are working to terminate her employment.

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