During which cognitive development stage can children demonstrate the understanding of conservation and reversibility?

The correct answer is that children demonstrate the understanding of conservation and reversibility during the Concrete Operational stage of cognitive development, as theorized by Jean Piaget. This phase, typically occurring between the ages of 7 and 11, is marked by significant advancements in a child's ability to think logically about concrete events.

During this stage, children develop the capacity to recognize that certain properties of objects, such as volume, mass, and number, remain unchanged despite changes in form or appearance—this is known as conservation. For example, if you pour liquid from one glass into a differently shaped glass, children at this stage understand that the amount of liquid remains the same.

Reversibility, another key concept, refers to the understanding that objects can be changed and then returned to their original form or condition. For instance, a child can grasp that if they have five marbles and take away two, they can also add those two marbles back to return to the original amount of five.

In contrast, the other stages would not encompass these abilities. In the Preoperational stage, which occurs prior to Concrete Operational (around ages 2 to 7), children's thinking is more intuitive and egocentric, and they do not yet understand concepts like conservation