A Dieruff High School math teacher offered a 16-year-old student extra credit if she texted him pictures of herself naked, police say.
Timothy C. Moll, 25, told the girl by text message that if she sent him the pictures and he was "turned on," she could earn extra points toward her grade, according to an arrest affidavit.
The 2005 Dieruff graduate also sent several texts of a sexual nature to the girl for two weeks starting Jan. 17, the court record states.
Moll, of 556 Evergreen St., Emmaus, was charged Wednesday with corruption of a minor and unlawful contact with a minor, third-degree felonies. He was arraigned by District Judge Michael D'Amore and released on $20,000 unsecured bail.

Allentown School District Superintendent Russ Mayo said Moll is on suspended administrative leave. Mayo wouldn't comment further, saying "it's a personnel matter."
Allentown teachers union President Debbie Tretter declined to comment.
The investigation began Jan. 31, after the student was sent to the assistant principal's office because she was using a cellphone in class.
According to the arrest affidavit:
The victim's mother was called to the school, and she told the assistant principal that her daughter was getting inappropriate text messages from Moll.
Allentown police obtained a court order for Moll's text messages.
In the texts, Moll asked the student to talk about sex and sexual positions. He then asked her to send naked pictures for extra credit.
This is the second time in less than a month that a Dieruff High employee has been charged with a crime.
Tim Geiger, the school's athletic director for the past 10 years, was suspended in March after the Lehigh County Drug Task Force arrested him on a drug possession charge.
In another Allentown case, Shawn W. Moser, an Allen High School security guard and middle school football coach, was charged Feb. 1 with trying to buy $20 worth of marijuana from a 16-year-old Allen student. He has resigned from both positions.
In December, Allen High teacher Gabrielle S. Marvelli was sentenced to nine months to five years in state prison after pleading guilty to a corruption charge for having sex with a student on prom weekend last year. The boy was a week shy of his 18th birthday.
District Attorney Jim Martin said he could have chosen not to charge her because the boy was nearly an adult, but said teachers should be held to a higher standard.
The Bangor Area School District has also had recent cases where personnel were implicated in sexual scenarios with students. A former Bangor Area High School teacher is charged with having sex with a 17-year-old student — authorities believe she may have had sex with up to three other students.
Rachel L. Farrell, 25, communicated on Facebook with the 17-year-old and had sexual encounters "numerous times at many different locations," according to court records.
Farrell was charged with corruption of a minor and in February gave up her right to a preliminary hearing. She is awaiting Northampton County Court action.
A nude photo of a Bangor teacher's aide made its way onto students' cellphones in 2010. The female aide was moved from the classroom to an administrative position.
Last week in Montgomery County, Nicole Jacques, 25, of Hatfield Township was charged with having sex with a boy she met while teaching at Calvary Baptist School in Towamencin Township. Detectives said she had a relationship with the 15-year-old after she left her job in 2011.