Following Piaget, schema theorists such as Rumelhart and Norman (1978), Skemp (1979) and others, have accepted the model of knowledge growth utilizing the twin processes of assimilation and accommodation. These offer parallels to the social constructivist accounts of subjective and objective knowledge growth. For knowledge, according to this account, is hypothetico-deductive. Theoretical models or systems are conjectured, and then have their consequences inferred. This can include the applications of know procedures or methods, as well as the elaboration, application, working out of consequences, or interpretation of new facts within a mathematical theory or framework. In subjective terms, this amounts to elaborating and enriching existing theories and structures. In terms of objective knowledge, it consists of reformulating existing knowledge or developing the consequences of accepted axiom systems or other mathematical theories. Overall, this corresponds to the psychological process of assimilation, in which experiences are interpreted in terms of, and incorporated in to existing schema. It also corresponds to Kuhn’s (1970) concept of normal science, in which new knowledge is elaborated within an existing paradigm, which, in the case of mathematics, includes applying known (paradigmatic) procedures or proof methods to new problems, or working out new consequences of an established theory.