Contrast the performance of preoperational and concrete operational children on the liquid and number conservation tasks

What will be an ideal response?

When shown two displays (cups of liquid or rows of coins), both preoperational and concrete operational children note that the quantities are equal. However, after one of the displays is transformed (e.g., the liquid from one container is poured into a new container with a different shape), preoperational children reason that one display has more than the other. For example, they may state that liquid poured into the new container "has more because it's taller." In contrast, concrete operational children reason that the quantities have not changed, and therefore, the displays are still equal in amount. Concrete operational children understand conservation of quantity because they focus on the dynamic transformation and recognize that it links the appearance of the two displays before and after the transformation. They also understand reversibility: that by pouring the liquid back into the original container, the original state can be recreated.