Miss Grinchley was Jason and Marcus's former 4th grade teacher. She got "flustered and bug-eyed" whenever Jason overdid one of his assignments. She retired over the summer one year, Mrs. O`Malley being her replacement. You never actually see her face but she is mentioned several times before she retired. Jason once made a comic on his desk that he labeled "Slug man battles Miss Grinchley" And got in a lot of trouble for it.