What is That Thing? & Buster's Best Behavior

What is That Thing?: Arthur and his friends separately find the same metal bobbin but do not know what it is. It happens to fit exactly what they need at the moment it appears. They argue over it and find out that it is Mr. Ratburn's bobbin and learn what it is at Mr. Ratburn's puppet show.
Buster's Best Behavior: Buster is funny but wants to be good at something else, and Arthur wants to be funny like Buster. They end up acting like each other. This annoys their friends and they realize that they are fine the way they are.