In a story about the U.S. Homeland Security office’s recent suggestion that American citizens apply plastic sheeting and duct tape to doors and windows in case of terrorist attack, CNNfn last night aired several scenes from “Duck and Cover,” a public domain film from 1951 that famously advised American school children to take shelter beneath their desks or under blankets in case of nuclear warfare.

As a product of the U.S. government, “Duck and Cover” was uncopyrightable and immediately entered the public domain. It is available for viewing online at the Prelinger Archives.

(Film archivist Rick Prelinger, you may recall, was our first featured commoner.)