Fat Albert and the Cosby Kids (1972)

The gang's classmate Patty was a straight-A student until she fell into the drug scene and now gets regularly high on marijuana. When the gang meets her drug pusher, Rudy is tempted to try it himself, but has a change of heart when he sees Patty in danger. He and Fat Albert are able to save her. They and a police officer meet with Patty's parents about her problem and she agrees to help get the pusher arrested, which is the first step on her road to recovery.