Mr. Grisbee is Keith Partridge's sex ed teacher and Laurie Partridge's biology teacher. He feels that Keith is an intelligent boy who does the bare minimum amount of work to pass, and that other teachers let him get away with doing less than he could because they like him. Mr. Grisbee is much harder on Keith than he is on the other students because he wants to push him to do his best. He tells Keith that his work isn't good enough for a passing grade. Shirley Partridge confronts Mr. Grisbee, accusing him of giving Keith a bad grade because he doesn't like him, but Mr. Grisbee says that Keith's work is subpar. Keith doesn't show up for the final exam. He does show up when Mr. Grisbee is testing another class, but Mr. Grisbee tells him to meet him at 3:00. When Keith meets him, he lies and says his friend ran over by a chicken and he had to give a statement to the police, but he eventually tells the truth: he's missed so much sleep while cramming that he fell asleep before the test. Mr. Grisbee lets Keith take the test, but he gives him a different one in case his friends gave him the answers to the original test. Mr. Grisbee gives Keith an A. Then he calls the Partridge house to say that he wants both Keith and Shirley to meet him tomorrow. When they show up in his classroom, he explains why he's been so hard on Keith. Keith thanks Mr. Grisbee and offers to rip up the note he was going to give to the principal accusing Mr. Grisbee of being unfair. Mr. Grisbee instead takes the note home to his nieces, who want Keith's autograph. Mr. Grisbee and his nieces are at the Partridge Family's next show.