Sean McCullough, an English teacher, is charged with endangering the welfare of a child and related offenses.
Prosecutors say McCullough taught the student from her freshman through senior years. They say the sexually inappropriate relationship began during her senior year, from 2009 to 2010.
The relationship allegedly included sexually explicit Facebook messages, emails, the exchange of nude photos and inappropriate sexual contact.
Prosecutors say in a statement to police McCullough admitted having an inappropriate relationship with the girl while she was a minor.
McCullough was arraigned Thursday afternoon.
The Methacton School District released the following statement from Superintendent of Schools Timothy J. Quinn:
Recently, the Methacton School District was informed that Methacton High School teacher Sean McCullough was arrested and charged with alleged misconduct related to a relationship with a student.
The safety and well-being of our students is our primary concern at all times. The District moved quickly to place this individual on administrative leave and is cooperating fully with the Montgomery County District Attorney's Office and the Lower Providence Police Department.
We appreciate our community's understanding with regard to the need for confidentiality whenever matters of personnel are involved. Our primary focus will be the needs of our students and families; and we refer any questions about the investigation and allegations to the office of the district attorney.
