Sandy L. Binkley, 36, a math teacher at Portland High School in Portland, Tenn., was arrested and charged with statutory rape of a 17-year-old student at the school.
A week after being charged, two more students told authorities they also had sexual relations with the teacher, at the school and off campus.
Binkley is now charged with three counts of aggravated statutory rape and one count of sexual battery.
She has been suspended without pay from The Sumner County school system.