This is not math class.
Math class definitely still exists--she can sense her classmates' and teacher's minds through the walls surrounding the door. But through the door itself, only one mind is perceptible.
...And it appears to be a bar.
Curious, Edie steps through the door and lets it close behind her. When it does, every mind but her own and the one in the room vanish. Even Emily's constant hum in the back of her mind vanishes.
Startled, she yanks the door open again. Everyone snaps back into focus. She examines the door carefully. It doesn't look like it could be lined with the same metal as Dad's helmet...
She lets the door close again, and turns her attention to the other mind in the room.