Final answer:
True, children in Piaget's concrete operational stage can think logically about concrete events and understand the concept of conservation.
Step-by-step explanation:
True, the third stage in Piaget's theory of cognitive development is known as the concrete operational stage, which occurs from about 7 to 11 years old. During this stage, children begin to understand logical operations and are no longer fooled by appearances. They can think logically about real (concrete) events, develop the concept of conservation, and become less egocentric, understanding that even if the appearance of something changes, the mass, volume, and number remain the same. A classic example is when children understand that the amounts of pizza remain the same regardless of how many pieces it is cut into, demonstrating an understanding of conservation.