The preschool educational television program Sesame Street was first aired on public television stations on November 10, 1969, and reached its 51st season in 2020. The history of Sesame Street has reflected changing attitudes to developmental psychology, early childhood education, and cultural diversity. Featuring Jim Henson's Muppets, animation, live shorts, humor and celebrity appearances, it was the first television program of its kind to base its content and production values on laboratory and formative research, and the first to include a curriculum "detailed or stated in terms of measurable outcomes". Initial responses to the show included adulatory reviews, some controversy and high ratings. By its 40th anniversary in 2009, Sesame Street was broadcast in over 120 countries, and 20 i