The School is where most of the things happens in Adventure High.
The Protagonist, Valerie, Cassandra, Sarah, Julia, Molly and Ashley (presumed formerly) are all students there. It's likely that Derrick is a student there, too. However, he's only present in a single scene as of version 0.37, making it hard to tell for sure.
There's five rooms in the school: Four classrooms and the Library. Next to the Library is the entrance to the Dungeon.
There's four teachers at the school:
Drape, the Debilibating Magic teacher and the main antagonist.
Dr. Tiff, the Support Magic teacher and school nurse.
Ms. Rack, the Physical Magic teacher and Val's aunt.
Jane, the Destructive Magic teacher, who seems to hide something from the Protagonist.