Blue's Clues
Malcolm Gladwell noted that Sesame Street appealed to both children and adults, but Blue's Clues was solely aimed at preschool children. They like stories, repetition and joining in the answers. Every episode of Blue was tested on preschool children, and the research noted how much of the time children watched the screen. The order of clues was tested. All aspects of the program could be changed if the testing suggested it would work better some other way.