Add Yahoo as a preferred source to see more of our stories on Google. Patrick Reese, general manager of CoComelon, stands near a shelf of toys at production company Moonbug's offices in Los Angeles.

Fifty-five years ago, preschoolers were captivated by the TV performance of a fuzzy blue monster, two striped shirt-wearing best friends and a big yellow bird. Today, in the now-crowded field of ...