Final answer:
According to Piaget, children enter the formal operational stage around age 11, which allows them to understand abstract ideas and hypothetical situations, significantly developing their cognitive skills.
Step-by-step explanation:
According to Piaget, children enter into the formal operational stage about age 11 wherein children begin to understand abstract ideas and hypothetical situations. During the formal operational stage, the final stage in Piaget's theory of cognitive development, children can use abstract thinking to problem solve, look at alternative solutions, and test these solutions. Prior to this, in the concrete operational stage, children can think logically only about tangible, concrete events. Moving into the formal operational stage, they become capable of thinking about abstract concepts, such as moral philosophy or algebra, and can process hypothetical scenarios. This reflects a significant growth in cognitive skills, allowing for more complex thought processes and the understanding that actions can have implications beyond the immediate.