1. The document discusses Jean Piaget's theory of intellectual development, which proposes that humans progress through four distinct stages from infancy to adulthood. 2. According to Piaget, children progress through the sensory motor stage from birth to age 2, the pre-operational stage from ages 2 to 6, the concrete operational stage from ages 7 to 11, and finally the formal operational stage from ages 12 to 15. 3. Piaget's theory posits that a child's environment and experiences are important for progressing through the stages of cognitive development.