Dr. Mertz is a science teacher that seems to want the students to enjoy his class, giving out awards such as a molecule hat to Screech. His Science test stresses Kelly because she has concert tickets that she won't get to use if she fails. Zack hoping to get on Kelly's good side arranges for Screech to tutor Kelly. The plan backfires when Kelly develops romantic feelings for Screech. Kelly manages to pass Dr. Mertz's test but finds that without the need for a tutor, she and Screech really do not have much in common.
He was only featured in one episode.