Sesame Street is an American educational children's television series that combines live action, sketch comedy, animation and puppetry. It is produced by Sesame Workshop and was created by Joan Ganz Cooney and Lloyd Morrisett. The program is known for its images communicated through the use of Jim Henson's Muppets, and includes short films, with humor and cultural references. The format of Sesame Street consists of a combination of commercial television production elements and techniques which have evolved to reflect the changes in American culture and the audience's viewing habits. With the creation of Sesame Street, producers and writers of a children's television show used, for the first time, educational goals and a curriculum to shape its content. It was also the first time a show's educational effects were formally studied. The show, therefore, has undergone significant changes in its history as adjustments to the format and content have been made to reflect change sources to the curriculum.