The attorney for 26-year-old Jonathan Crum, of Slippery Rock, didn't immediately return a call Tuesday on charges filed Monday by state police. Crum was jailed unable to post $100,000 bail.
Police say the contact took place at Moniteau High School about 35 miles north of Pittsburgh since 2009.
Police believe there may be other victims in the case and say they filed the charges after interviewing the current and former students last month.
School officials say they're cooperating with the investigation. Crum faces a preliminary hearing May 23.