Updated: Jul 3, 2018
As the title implies, this is a floating island that is home to a school. The island floats due to the bubble on top of the rubble pulling it up into the vapor. The islands around the Sky School are so small and light that they don't need a bubble to float.
The bubble itself protects the Sky School from harmful weather. For example, the lightning that is hitting the bubble in the drawing will just be absorbed and redirected off the other side if it's too much to absorb or it may even just become discharged.
The Blimp shown heading to the entrance of the Sky School, the arc, is for students who were picked up from their homes to attend school.
The school also houses dorms for both boys and girls but those are behind the school itself along with a track field and the ancient Mayan ball game, Pitz.
This school is called the Peace Core Academy. They train individuals to become Officers in The Peace Core when they graduate.
Note: All floating islands in layer one have a bubble around them.