Piaget’s Theory of Cognitive Development in Middle and Late Childhood. - Concrete Operational Thought - Concrete operational thought encompasses operations, conservation, classification, segregation, and transitivity. Thought is not as abstract as it becomes later in life. This period lasts between seven and eleven years. - That is, the years of middle school. Children reach this stage when they are capable of decentering and mentally reversing acts. As a result, they can use the conservation principle. Evaluating Piaget’s Concrete Operational Stage - Critics contend that aspects of a stage do not arise simultaneously, and that knowledge and education have a greater impact on development than Piaget envisaged. - Neo-Piagetians put more attention on how children acquire information, tactics, information processing speed, and cognitive division.