Today our educational system is undergoing a paradigm shift to problem based learning. Class rooms are now changed to a place where students think reasonably and solve problems logically. Models are prescriptive teaching strategies designed to accomplish particular instructional goals. It creates the conducive teaching –learning environment in which students construct their own knowledge. Teachers are seeking for effective models that can unravel each child’s potential for learning. Cognitive Development Model is designed to instruct students in higher order thinking, formal reasoning, problem solving, abstract and deductive thought. This book presents a study on the effectiveness of Jean Piaget’s Cognitive Development Model on achievement in Physics of secondary school students. Hence it enables the beneficiaries to get a clear idea about the Cognitive Development Model and its effect on learning.