There seems to be some great information available regarding Piaget’s Theory of Cognitive Development.
Here is a useful link on the subject matter.
Although there is no general theory of cognitive development, the most historically influential theory was developed by Jean Piaget, a Swiss Psychologist (1896-1980). His theory provided many central concepts in the field of developmental psychology. His theory concerned the growth of intelligence, which for Piaget meant the ability to more accurately represent the world, and perform logical operations on representations of concepts grounded in the world. His theory concerns the emergence and acquisition of schemata—schemes of how one perceives the world—in "developmental stages," times when children are acquiring new ways of mentally representing information.
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