Sensorimotor (Birth–2 years)

Infant experiences world through movement and sense, develops schemas, begins to act intentionally, and shows evidence of understanding object permanence.

Preoperational (2–6 years)

Child acquires motor skills but does not understand conservation of physical properties. Child begins this stage of thinking egocentrically but ends with a basic understanding of other minds.

Concrete operational (6–11 years)

Child can think logically about physical objects and events and understands conservation of physical properties.

Formal operational (11 years and up)

Child can think logically about abstract propositions and hypotheticals.