This document summarizes Jean Piaget and Lev Vygotsky's theories of cognitive development. It outlines the key concepts of Piaget's theory, including schemas, assimilation, accommodation, equilibrium, and the four stages of cognitive development from sensorimotor to formal operational. It also discusses implications for teaching based on Piaget's theory. For Vygotsky, it mentions his focus on social learning and the zone of proximal development.