School shooter drills are the modern version of 'duck and cover drills' from the 50's and 60's. https://www.britannica.com/topic/duck-and-cover https://www.bri

School shooter drills are the modern version of 'duck and cover drills' from the 50's and 60's. https://www.britannica.com/topic/duck-and-cover https://www.britannica.com/topic/duck-and-cover