Many researchers have written about child development, but the best known are Jean Piaget and Lawrence Kohlberg. Piaget's theory of cognitive development and Kohlberg's theory of moral development have been instrumental in helping researchers understand the biological and psychological changes that occur between birth and adolescence. Although these theories share some similarities, they also have many differences, such as Kohlberg's application to various cultures. It is important to compare these models in order to understand child development. Jean Piaget (1896-1980) was a Swiss prodigy and psychologist. After graduating from the University of Zurich, he moved to Paris, where he taught at the Grange-Aux-Belles school for boys. While at the school, Piaget noticed that “children of the same age tended to give the same wrong answers, while children of a different age tended to give different wrong answers” ​​(Cook, 2009 , p.153). This led him to believe that rational processes develop over time. According to his theory of cognitive development, children grow through four different stages. Piaget's first stage, sensorimotor thinking, begins at birth and continues until approximately age two. This is the world of infants and young children, who experience the world solely through their five senses. Piaget divided this first stage into six sub-stages. The first sub-stage is basic reflexes. At birth, infants have only instinctive reflexes, such as rooting, sucking, and grasping. When the child reaches about a month old, he or she moves on to the next substage called primary circular reactions. At this stage, the child begins to learn through trial and error. Thumb sucking is one such example o...... middle of paper ......lopment.References(1980). Moral development, moral education, and Kohlberg: fundamental questions in philosophy, psychology, religion, and education. In B. Munsey (ed.). Birmingham: Religious Education. Cook, J.L. and Cook, G. (2009). Child development: principles and perspectives (2nd ed.). Boston: Pearson Education. Crain, W. (2005). Theories of development: concepts and applications (5th ed., pp. 118-136). Upper Saddle River, NJ: Prentice Hall. Duska, R.F. and Whelan, M. (1975). Moral development: a guide by Piaget and Kohlberg. New York: Paulist. Kohlberg, L., Colby, A., Gibbs, J., Speicher-Dubin, B., & Power, C. (1977). "Assessing Moral Steps: A Handbook, Part III". Thesis, Harvard University, Cambridge, MA.Power, C. and Kohlberg, L. (1981). The philosophy of moral development: moral stages and the idea of ​​justice. Thesis, Harper & Row, San Francisco.