Pleasure Campus: Secret Games (1980)

A high school girl has a very very bad day. She is disciplined for disrupting class and sent to clean lab equipment. Feeling horny she uses a phallic looking test tube to pleasure herself. Unfortunately a passing teacher spots her and proceeds to further discipline her with additional equipment. She suffers as a parade of teachers dish out a variety of humiliations one after another. Finally escaping to home she finds her trials are not over as her parents decide to give her a rather perverse sexual education.