In late 1939, the United States Bureau of the Census was gearing up for the 16th official enumeration, or count, of the nation's population. Authorities wanted to insure widespread participation. So, they made good use of some information revealed in the 1930 Census--namely that roughly 40 percent of American households had a radio set. In collaboration with the United States Office of Education, the Bureau created a series of Public Service Announcements (PSAs), titled "Uncle Sam Calling," that citizens and residents could hear on their radios. The announcements emphasized the importance of participation. In addition to the radio PSAs, the Bureau also created a four-and-a-half-minute film titled "Know Your U.S.A." that movie-going Americans might have seen in a theater before a feature film. This article demonstrates how educators can teach their students using documents such as "Uncle Sam Calling," and the short film "Know Your U.S.A."