Final answer:
Children learn conservation and begin to understand others' points of view in Piaget's Concrete Operational Stage
Step-by-step explanation:
In Piaget's four stages of cognitive development, children learn conservation and begin to understand others' points of view in the Concrete Operational Stage (C). This stage occurs from about 7 to 11 years old. During this stage, children can think logically about real events and concepts. They develop an understanding of conservation, which is the idea that even if something changes in appearance, its mass, volume, and number remain the same.