32-year old Jenna Leahey, a teacher at Parsippany Hills High School, is charged with endangering the welfare of a child and criminal sexual contact.
Prosecutors say the relationship started in late January 2013 when Leahey began exchanging sexually explicit text messages with the student and later sent sexually explicit pictures of herself to him.
The relationship allegedly progressed physically to acts of kissing and mutual sexual contact and continued through June 6, 2013.
Prosecutors say the acts occurred on and off school grounds. The student disclosed the relationship to a staff member at the school.
The school is cooperating with the investigation.
Bail was set at $100,000.