Used to be schools had entrances all over the building, that were always open during school hours.””’
I went to a one room school There was only one entrance. Guess that wouldn’t pass today’s fire codes-—we would have had to exit thru the windows if there ever had been a fire.
Our school still has doors all around the school, so there are exits all over the place. But, you can’t enter through those doors. And in case if a “lock-down” all those doors can be chained up and locked, during that lockdown period.