Born in Switzerland, Jean Piaget sought to answer one question in his life work: How does knowledge grow? He studied his three children and thousands of other children to answer this question. Piaget spent his time watching children play and playing with them. He told them stories and listened to their stories, asking them questions about why things are as they are. He invented problems for them to solve and asked them what they dreamt about.
What did Piaget discover? He discovered that knowledge builds as children grow. Children develop logic and think differently at different ages. Psychologists regard Piaget’s discovery as revolutionary and insightful. Piaget’s theory challenged the behaviourists’ view that the environment determines behaviour. Piaget stressed a child’s active role in gaining knowledge. For these contributions, many consider Piaget the greatest child psychologist of the twentieth century.