much like our modern government prefers to keep the populace in a constant state of low-level fear (terror alert level orange, anyone?) so too did the post-war, atomic age government.
but along with the fear, they had to temper it with reassurance. you don't want the populace holing up in their houses or running screaming through the streets firing weapons.
so they made films like this famous 'duck and cover' educational film made to be shown to schoolchildren in 1951.
remember kids: a nuclear explosion could burn your skin, much like a very bad sunburn -- unless you're under your desk!!!
UPDATE: sorry if this clip is fucking autoplay for you too. if you use firefox (and you should) get the Noscript add-on. once it's installed, right-click this page and disallow blogspot. then you can just click on the individual clips you want to view.