Binky worries that everybody will treat him like a baby if they they find out he still holds his mother's hand in public. The Tibble Twins have a falling out after Tommy discovers he can whistle loudly and Timmy cannot.
Buster gets a mysterious box of chocolates and tries to track down who the gift came from. Meanwhile James gets a new toy lamb from his uncle and wonders if it contains special powers.
Mr. Ratburn sets up a week-long experiment where nobody in class can spend any money. Meanwhile Buster purchases a new Dark Bunny toy that seems to have a mind of its own.
Buster begins to wonder about the strange chemicals in a trendy new candy bar for sale. Meanwhile Arthur and the gang worry about how to pass their first standardized tests.
Binky is embarrassed to learn that his real name is Shelly, but then he learns the cool history behind it. Meanwhile Arthur and Rubella try to help Prunella break her hoarding habit.
Muffy gets Bailey to help her set up a book club for her favorite doll-themed series, but finds that her friends have their own personal tastes. Meanwhile D.W. tries to befriend a new girl her age, with hilarious results.
Buster runs into trouble while agreeing to watch over his friend Fritz's community garden. Meanwhile Arthur gets new hipster glasses to replace his old ones, giving him a huge and annoying ego.
Bailey goes missing, and Muffy realizes to her regret that she never really treated him like a dear friend. Meanwhile Fern is bothered for not wanting a trophy.
Arthur and D.W. get worried when Grandpa Dave begins to forget everything, but he assures them that this is common with older people. Meanwhile Buster has to carpool with friends.
