Mr. Wizard, an early children's television pioneer, made his debut way back in 1951. In Watch Mr. Wizard, Don Herbert showed kids the wonders of science and experimentation. The program lasted more than a dozen years on NBC and the Mr. Wizard persona was reintroduced in the 1980s on Nickelodeon. This episode appeared in 1954:
Over the years, children's television has become more sophisticated, as has its hosts, and the topics explored. Science always remains a fascinating subject to kids. Bill Nye the Science Guy, ran for 100 episodes on PBS in the 1990s. Today, Bill Nye is attempting to educate adults in the transformative power of science. Look for Unstoppable: Harnessing Science to Change the World [AB/CD 363.73874 NYE, also ebook].
PBS programs continue to cover science topics. Dragonfly TV came along in the 2000s, and was followed up by SciGirls.