 He responds by becoming a Pony Express courier who braves a horde of Indians on what becomes his desert journey.Back in the classroom, he finds the geography lesson tedious until the sight of a fish in an aquarium triggers his next daydream — as a deep-sea diver, without gear, who kills a shark which is guarding an immobilized submarine.He then lifts the submarine, allowing it to float freely to safety (on board is Miss Wallace dressed as a nurse; she holds up a sign reading, "Oh, thank you, thank you, Ralph!