Ep 9. What Is That Thing? / Buster's Best Behavior

Arthur season 4 episode 9 is titled "What Is That Thing? / Buster's Best Behavior." In the first half of the episode, "What Is That Thing?," Arthur’s class is visited by a strange new student named Wally, whose appearance and behavior are puzzling. The students are all curious about Wally and try to get to know him better, but just when they think they’ve figured him out, they are surprised by his next move. Meanwhile, Arthur has trouble concentrating on a science project and falls behind on his assignments.

In "Buster’s Best Behavior," the second half of the episode, Buster tries to prove to his mom that he can be responsible by taking care of his grandma’s cat. Buster is determined to show everyone that he can be trustworthy and reliable, but keeping up with the cat’s needs proves to be difficult. When things get out of hand, Buster learns an important lesson about taking responsibility for his actions.

Overall, "What Is That Thing? / Buster's Best Behavior" is a heartwarming episode about learning to accept and embrace those who are different from us, and about the importance of taking responsibility for our actions. The combination of humor and valuable life lessons makes this episode a must-watch for fans of Arthur of all ages.