Jean Piaget was a developmental psychologist who was born in Switzerland in 1896. He was most famous for his theory of cognitive development. Piaget's theory states that as children develop biologically they also meet specific cognitive goals. Developments of adaptive behaviors are connected to mental development. These are obtained in specific chronological stages. Piaget's theory contrasts to other developmental theories by focusing on the development of intellect. Piaget contributed the idea that children's minds grow gradually, and that they are not capable of reasoning like adults.

Clarify the ways in which Piaget linked behavior with cognitive development. Explain that for Piaget, humans adapt to their environment using schemes -- that is, ways of organizing ideas. The cornerstone of Piaget's theory is that children have different ways of seeing the world that grow and change along with their biological growth. Explain that as children start to interact with the world they organize ideas into groups or "schemes." This is similar to the reflexes that animals use to adapt to their environments; however, human schemes go beyond reflex and involve independent cognitive abilities.

Define the processes of assimilation and accommodation. Piaget theorized that intelligence is a form of evolutionary adaptation and that humans adapt to the environment through strategies he called assimilation and accommodation. Give examples of these to make the difference clearer to your students. Assimilation is transforming the environment in order to make it fit preexisting cognitive schemes -- as when an infant knows how to suck on a large bottle after sucking on a smaller bottle. Accommodation, on the other hand, is changing schemes to accept the environment -- as when a child modifies her scheme for sucking on a pacifier to one that will work for sucking on a bottle.

Elucidate Piaget's theory by explaining his stages of cognitive development. Explain that Piaget based these stages on biological development and believed that chronological stages of mental development are related to brain growth. Describe Piaget's four stages and give examples for each stage. For instance, when describing the concrete operational stage, explain that this occurs for children in elementary school and early adolescents. Give the example that prior to this stage, when a child looks at two glasses of water of different shapes, but the same amount of water she will assume that of two cups containing the same amount of liquid, the taller, thinner one contains more than the shorter, wider one.