Jean Piaget is known all over the world for his work in the fields of psychology, sociology and education. He theorized that children’s logic and modes of thinking were initially entirely different from those of adults.
After years of research in developmental psychology and genetic epistemology, Piaget came to believe that intelligence is a form of adaptation; that the child adapts to his physical and social environment through the processes of assimilation and adaptation, constructing his own intellectual world. He believed that a child’s development occurred in four distinct stages: Sensory Motor - Birth to approximately 2 years, Preoperational - typically lasting until ages 6 or 7, Concrete Operations lasting until ages 10-12 and finally the Formal Operations stage.
One important principle of Piaget’s stage theory is the idea of genetic constraints meaning you can present new ideas and challenges to a child but you cannot "teach" a child out of one state into another. In addition, a child cannot acquire new, increasingly complex knowledge without interacting with his environment thus linking nature and nurture.
Piaget’s research was extensive and his theories have greatly influenced the field of education. They require study for proper understanding which would include reviews by proponents as well as critics of his theories.