When Duck and Cover first appeared it actually made sense. Delivery systems were very limited. The likelihood of more than one bomb on a city was limited. The bombs themselves were small by later standards, fission not fusion. A 50kt exploding 5K ft over Times Square would break windows in eastern Queens. The mocking of Duck and Cover is valid as delivery systems and explosive power grew exponentially, but when I was doing it in the early grades it may well have worked.
Good point—and of course in those days there were actual fallout shelters which would have probably saved a lot of lives in that time frame.
When I was ducking and covering as a grade schooler in a school on MCAS Beaufort it likely would not have worked.
Although the Cuban missile crisis did add a sense of urgency...
...as did not knowing where dad was until we saw his squadron's aircraft in the Sunday funnies!
I never knew about duck and cover until I went to a public school later on. I was young, had no idea what an atom bomb could do. I remember kids crying. For me it was just a game.