They were still doing that in the 60s when I was in elementary school. To this day, whenever I see a tall flag blowing in a bright blue sky on a chilly day I ALWAYS flash back to taking that position on the school playground during a drill. Don't know why. I wasn't scared that I recall. But it was the only time I was outside during a drill and I remember peeking up, looking for bombs and seeing the flag in the sky.