The Psychology of the School Subjects. Judd's efforts at the University of Chicago to develop the psychology of the school subjects also proved popular with mathematics educators. “No other school subject has even approached the level and frequency of studies conducted in the area of arithmetic” (Shulman, 1970, p. 25). Judd tried to relate the learning of complex subject matter to basic psychological processes in a way that would avoid Thorndike's reductionism. To Judd, each subject had its own facts and generalizations that needed to be understood before that knowledge could be used. Judd (1928). contended that Thorndike's view of arithmetic as a tool subject was false Instead, arithmetic is a “general mode of thinking" (p. 6). "It is the business of the school to transmit to the pupils the intellectual methods of arrangement by which the complexities of the world may be unraveled and a new pattern made of experience. The most comprehensive and flexible patterns for the rearrangement of experiences are those supplied by the mathematical sciences" (p. 8). Although Judd often stressed the importance of studying the learning of secondary school subjects and not just those from the elementary school, his own research concentrated on simple concepts from arithmetic (Judd, 1927). Similarly, both his student Guy T. Buswell and his and Buswell’s student William A. Brownell, developer