I know what you're thinking. "Ridiculous. Everybody this side of the 1950s knows that's not going to do anything." But bear with me; there's more to it than you think.
First, a quick history lesson. At the close of World War II, the United States boasted the world's only nuclear arsenal. Then the Soviet Union successfully tested some weapons of their own in 1949. As you've probably heard, those countries didn't get along very well, so in response, the United States formed the Federal Civil Defense Administration in 1951.
As part of the agency's mission to educate the public about nuclear preparedness, the film "Duck and Cover" was born. It featured a turtle named Bert who helped show children how to duck under desks and cover their heads when they saw a bomb detonate.
Crazy, huh? Not completely. When the film came out in 1951, scientists figured the main dangers from a nuclear attack were the blast and the heat. They didn't fully understand the whole radiation thing yet. And the atomic bombs of the time, though devastating, were like firecrackers compared to the hydrogen bombs tested the next year. Given the circumstances, duck and cover made a certain amount of sense [source: Kelly].
Of course, these drills continued long after officials fully realized the effects of radiation and the power of the hydrogen bomb. But it was a scary time, and people needed to feel like they could do something — even if they might be vaporized doing it.