I'm going to guess Boo Radley.
well it says here in the exerpt that they bursted out in to laughter showing they thought that was a joke.
Answer:
The poet presents the ways children see their own world as being delightful. They 'dance' and 'play' in this world. This tells us that they are happy there. It is a world adults don't understand because they 'cannot find the centre'.