1. Jean Piaget's theory of cognitive development consists of four stages: sensorimotor, preoperational, concrete operational, and formal operational.
2. Each stage is characterized by developing schemas, or ways of thinking, and by the use of assimilation and accommodation to adapt to new information.
3. In the concrete operational stage from ages 7-11, children begin to think logically about concrete events and understand concepts like reversibility and conservation, though they still struggle with abstract thinking.