Fern dares Arthur and his friends to enter the poetry writing contest at the local library, but writing poems turns out to be harder than they thought.
Arthur really wants to enter a song in the Crunch Cereal Jingle Contest, but when he cannot come up with a good idea, he enters a song his sister wrote instead.
Arthur's Grandma Thora, a marbles champion, trains him for the first-ever Elwood City Marbles Tournament, but does not tell him that she will compete against him.