Over a period of 60 years the psychologist Jean Piaget developed a wide-reaching theory of child development. Piaget was interested in how knowledge developed in human organisms, and he called his theoretical framework "genetic epistemology." Piaget’s theory suggests that the cognitive structures of an individual change through the processes of adaptation: assimilation and accommodation.
Adaptation is Piaget’s term for what we would traditionally call learning. But Piaget saw adaptation as biological process; he points out that all living things adapt to their environment even if they lack a brain or nervous system. Piaget suggests that the human organism adapts to its existence and the world around it via assimilation and accommodation.
Assimilation, in Piaget’s theory, involves the interpretation of events in terms of existing cognitive structures. That which is perceived in the outside world is interpreted in relation to that which is already known. For example, a child knows how to grab his favorite toy and thrust it into his mouth; this knowledge Piaget terms a schema. When the child comes across another new object--say a television remote--the child transfers the “grab and thrust” schema to the new object. In this way, the child interprets new phenomena using existing knowledge. The child adapts but without changing his world view.
Accommodation, in Piaget’s theory, is where an individual's internal world has to change to adapt to new phenomena in the external world. When accommodation takes place, it is because the individual world view is not capable of fitting with external reality. The internal world must shift so it correlates with reality. For example, if a child moves away from the television remote and finds a ball, he will try to use assimilation and the “grab and thrust” schema but without achieving the desired result. The child must, through the process of accommodation, learn a new approach so as to interact with the ball. The child develops a new “squeeze and bounce” schema. Accommodation is a more painful form of adaptation than assimilation because an individual’s conception of reality has to shift.
Piaget’s theory of adaptation, assimilation and accommodation applies to the cognitive, intellectual and moral development of an individual throughout her lifespan. Piaget’s theory has been applied extensively to teaching practice and educational curriculum design.
Piaget’s theory suggests that, regarding education, children have a different conception of reality at different stages of their development and that cognitive development is facilitated by the child's exposure to new phenomena. Thus education should involve both the child’s exposure to new phenomena and an approach suitable to the child’s current conception of reality.