Jean Piaget was a Swiss psychologist who studied how children learn. He believed that kids go through stages as they learn and develop. He said that kids between the ages of 0 and 2 learn by exploring and experimenting with things. He also said that kids between the ages of 2 and 6 use logic and reasoning to understand things. Finally, he said kids between the ages of 6 and 12 use logic and understanding to figure out how things work. He also thought that kids learn best in an active environment where they can explore, question and practice new skills.