Mister Rogers brings an empty aquarium. Yen Wang visits with two rats which he puts into the aquarium. Dr. Wang explains that the rats are used for experimental purposes so that more can be learned for the benefit of human beings. Although one rat is black and the other is white he says they are the same inside. He demonstrates how he makes the trolley come and go. In the Neighborhood of Make-Believe, Lady Aberlin takes Bob Dog to the opening of the new pie restaurant. King Friday is afraid of Bob Dog and orders him to Someplace Else. Donkey Hodie welcomes Bob Dog.