Illustrates public television's early commitment to children's programming, discussing the popularity of "Sesame Street" and noting other shows launched under Joan Ganz Cooney, president of CTW from 1970 until 1988. Discusses the erosion of television network ratings by cable television in the mid '80s, and concludes by posing questions (to be answered in the next issue) on the value of "Sesame Street" for underprivileged children. (AEF)