why do schools have fire drills ?

I think schools have fire drills because it shows them were the escape route is in case their is an actual fire. If we did not no were to go when their was a fire i am sure this school would be in absolute chaos with hundreds of students running around tying to get out of the school. Kids would be running around loose and the teachers would not be able to keep track of them and make sure that they are out of the building safely.