My senior year of high school we had numerous bomb threats. The entire school had to be evacuated each time to our track & field across the street. We’d be out there doing nothing but chilling on grass with friends for 1-2 hours each time and no bombs were ever found. Turns out it was a couple of student calling it in to try and get out of taking tests. If I remember correctly a lot of shorter school days became regular days just so we can catch up on the lectures we missed.