Final answer:
Children in Piaget's concrete operational stage improve in logical reasoning, conservation, and classification but not in abstract thinking, which develops in the formal operational stage.
Step-by-step explanation:
Children in Piaget's concrete operational stage show increased skills in various areas as they are able to think more logically and understand complex concepts. They exhibit improvements in logical reasoning, understanding conservation, and are better at classification. However, they do not yet excel in abstract thinking, which involves thinking about things that cannot be seen, heard, or touched, and is a skill that further develops in the following stage, known as the formal operational stage. In summary, the concrete operational stage sees advancement in reasoning about real, tangible concepts but not in abstract thinking.