The document discusses several theories of cognitive development, including those proposed by Piaget and Vygotsky. Piaget's theory focused on how children actively build knowledge through schemas and adaptation processes like assimilation, accommodation, and equilibration. He proposed four stages of cognitive development. Vygotsky emphasized the important role of social interaction and culture in children's learning and cognitive development. The document provides details on the key concepts and stages in Piaget's theory of cognitive development.