Alcatraz Elementary School is the largest of the five nightmare realms in the Nightmare Ned video game. The entryways are marked by an apple icon. It is controlled by the School Shadow.
The game's instruction manual says that the nightmare highlights the anxieties with school, from being picked last for a sports team, to no one wanting to sit next to you at lunchtime.
The school itself is basically set up like a prison compound, representing Ned's interpretation of school, having barred windows, mugshots of students posted on the walls, barbed wire lining the walls, and so on. The Nightmare represents Ned's fear of school, homework, and bullies.
When selected on the quilt, Ned will fall down to a long tunnel and find a ladder to the Alcatraz Elementary School.