Hunter R. Reeser, of Harborcreek Township, is being charged as an adult with first-degree murder.
Authorities say he shot 60-year-old Sandra Orton with a .22-caliber rifle on Tuesday. He then called her husband and claimed he found her wounded.
But he later called 911 and confessed to killing her, police said.
Cops found Orton dead in her vehicle, shot in the head.
Reeser later told authorities that he didn't want to go to a school meeting.
In Pennsylvania, children must be charged as adults in murder or homicide cases.
Reeser is being held without bond.