Author Christopher Finch reported that director Jon Stone, who had worked with Henson previously, felt that if they could not bring him on board, they should "make do without puppets".
The Muppets were effective teaching tools because children easily recognized them, they were predictable, and they appealed to adults and older siblings.
[4] During the production of Sesame Street's first season, producers created five one-hour episodes to test the show's appeal to children and examine their comprehension of the material.
The producers decided to reject the advisers' advice and reshot the Street segments; Henson and his coworkers created Muppets that could interact with the human actors,[8][9] specifically Oscar the Grouch and Big Bird, who became two of the show's most enduring characters.
[10] These test episodes were directly responsible for what writer Malcolm Gladwell called "the essence of Sesame Street—the artful blend of fluffy monsters and earnest adults".