Piaget discovered that all children’s cognitive development progressed through four stages, beginning in infancy and are completed by adolescence.
Thinking becomes more and more complex as the child ages. Each stage of thinking causes the child to see the world in a different way.
The following article "Jean Piaget - Cognitive Development" provides information on Piaget's 4 Stages of Cognitive Development and how you can incorporate Piaget's theories into practice.
To read the article: Jean Piaget - Cognitive Development