When Buster defeats the Brain in a math contest, he is chosen for the school mathathon. Crushed, the Brain says he's decided to become a comedian and declares Buster the new "brain."

Arthur and his friends help Buster study for an important test so that he will be able to move on to the fourth grade with them.

When Buster impulsively drops a Cybertoy into Arthur's backpack in the drugstore one day, he feels so guilty that he finally confesses to his friend and they try to return the popular toy before anyone else finds out.

Arthur needs to decide how much he wants to learn the piano after his teacher dismisses him for not practicing.

Rumors about sightings of an alien space ship create excitement when Arthur's friends come to spend the night.

Arthur doesn't believe that his little sister can really read, so he challenges her to prove it.

D.W., a young anteater, discovers that lots of practice eventually helps her master the new routine in her gymnastics class.

Arthur the aardvark catches chicken pox a week before he is supposed to go to the circus.

Arthur is unhappy about going on vacation with his family, but he shows them how to make the best of a bad situation when they end up stuck in a motel because of rain.

Arthur becomes so involved in helping his friends complete their class projects on Elwood City that he runs out of time to do his own.