fire drill
A practice to safely leave a building in a fake fire.
A fire drill is a practice evacuation where everyone in a building pretends there's a real fire and follows the emergency exit procedures. Schools, offices, and other buildings hold regular fire drills so that if a real fire ever happens, everyone already knows exactly what to do: where to go, which exits to use, and where to gather outside.
During a fire drill, an alarm sounds and everyone stops what they're doing and calmly walks to the nearest safe exit. Teachers take attendance outside to make sure no one is missing. The whole process usually takes just a few minutes, but those few minutes of practice could save lives in a real emergency.
The drills might seem like an interruption to your math lesson or a chance to stand outside for a bit, but they serve a serious purpose. When people practice something over and over, they can do it automatically even when they're scared or confused. Firefighters and pilots run drills constantly for the same reason: when an emergency strikes, your practiced response takes over.
The term has also expanded beyond actual fire safety. People sometimes say they're running a fire drill when they're practicing any emergency procedure, or describe a hectic, urgent situation as like a fire drill.