During which developmental stage does a child begin to understand the concept of conservation?

The correct choice is based on developmental psychology, specifically referencing Jean Piaget's theory of cognitive development. During the concrete operational stage, which typically occurs from ages 7 to 11, children begin to grasp the concept of conservation. Conservation refers to the understanding that certain properties of objects, such as volume, mass, and number, remain the same despite changes in the form or arrangement of those objects. For instance, a child in this stage realizes that if water is poured from a short, wide glass into a tall, narrow one, the amount of water stays the same even though it looks different.

In contrast, the preoperational stage, which occurs from about 2 to 7 years, is characterized by symbolic thought but lacks logical reasoning, meaning children in this stage do not yet understand conservation. The formal operational stage, starting around age 12, involves more abstract and logical thinking but does not specifically relate to the concept of conservation, as that understanding is established earlier. The sensorimotor stage, occurring from birth to about age 2, is focused on experiencing the world through senses and actions and does not involve understanding the conservation of quantity or volume at all. Therefore, the concrete operational stage is pivotal for developing the ability to understand conservation