I was born in 1947 in Rochester, NY. I went to grammar school in the 50's. They did not use duck and cover in that school system. In fact, when air raid drills were conducted, each classroom was told to file out into the hallway, and sit on the floor on both walls of the hallway. There was a large window at the end of the hallway, and smaller windows higher up on the outside wall of the hallway. I don't recall air raid drills in high school (1960-1965). If they had amounted to anything, I would have remembered them.
Same for me in the ‘50s and ‘60s in school near Buffalo. No duck and cover. But we went to the hallway walls, stood up facing them, with our head in crossed arms.
The only thing separating our house from the air raid siren was a church and a town hall. THAT sound was terrifying!