In the beginning, there was the dummy. Long before Dora the Explorer, children's television was dominated by a freckly marionette and his pal Buffalo Bob. Howdy Doody's template--a vaudevillian romp full of wacky characters and make-believe--was followed well into the 1960s, picked up by shows like Captain Kangaroo and Bozo's Circus. (Before syndication, early children's programs were franchised across the country; at one time there were more than 200 Bozo the Clowns working U.S. airwaves.)
But while these shows were fun, they were far from educational. It wasn't until the debut of Sesame Street on Nov. 10, 1969, that TV became...