Arthur and his friends are assigned to write about what they do over the weekend, but the rain ruins plans. Arthur and D.W. bother each other and are sent to Grandma Thora's, where Thora shows them old home movies and comic books that give Arthur a great idea for his assignment. Grandma Thora is oblivious to the fact that she is a poor cook, and when she bakes cookies for a school bake sale, Arthur and D.W. try to stop her bad cooking from ruining the bake sale without hurting her feelings.