Pop-Up and other movable book formats have been used as marketing collateral since at least the middle of the 1800s. As early as 1902, for example, the Kellogg Company included slender flap books in cereal boxes. Their original product, known as Toasted Corn Flakes, was initially advertised as a healthy breakfast food for children. Undoubtedly, tucking a paper toy in a cereal box appealed to children, who would ask their parents to buy the product. Did the gimmick work? Yes, apparently, because by 1909 Kellogg’s was producing 120,000 boxes of corn flakes every day.