In some cases, authors have used the term "factory model" as a metaphor.[12][13] As a modern example, the animation and text of Sir Ken Robinson's TedTalk compares students in schools to materials in a factory and references children's "date of manufacturing" as a sorting mechanism. This clearest example of this in historical writing is in the research of Raymond E. Callahan, especially in Education and the Cult of Efficiency (1962).[14] Callahan explored the relationship between public education and the emerging concept of Scientific Management in the 1910s and included quotes by school leaders who spoke of children as the "raw goods" schools were meant to mold into something better. The most prolific user of this analogy was Ellwood Patterson Cubberley.