Here's a few mission ideas that would fit the school PoI very well
-Fire alarm activation (School): Requires 1 Fire truck, 1 ladder, 1 chief. Works like a smoke investigation mission and can upgrade to a room fire
-Cafeteria Fire: A grease fire out of control! Requires 3 fire trucks, possibly one chief, and might have 2-3 casualties
-Chemistry lab accident: An experiment has blown up in a student's face! Requires 1 Fire truck, one Ambulance, and 75% chance for hazmat