A teacher at Slippery Rock Middle School has been charged with felony institutional sexual assault and corruption of minors, after allegedly touching four girls inappropriately in math class at the school.

Robert P. Willison, 51, of Slippery Rock, allegedly touched three of the girls at different times during the month of September, according to court documents. It was unclear from a police affidavit when the fourth girl was allegedly touched.

Police said the charges come after a complaint filed against Willison, who teaches 8th grade math, with ChildLine, the state's avenue for people to report suspected child abuse.

According to the office of district Judge Bill O'Donnell, Willison has made arrangements to turn himself in to police on Monday.