Answer:
Milo learn how much fun it is to learn.
Step-by-step explanation:
The main themes of The Phantom Tollbooth are education and boredom. The adventure from which Milo pass through help him to learn many things but the most important thing he learned is that the adventure help him learn how much fun is present in learning new things. The story also provide us information that the people can bored even in the craziest of places.