Children's Perception of Conservation of Liquid

One stage of Piaget's four-part division of cognitive development is the stage of concrete operations, which lasts from approximately age seven to age eleven. During this stage children are involved in discovering rules and understanding the reasons for them. The hallmark of this stage is conservation: the ability to recognize that objects that have been transformed in some way, such as by undergoing a change in shape or placement, remain the same objects and represent the same amount of weight and/or volume.

In a typical conservation task, a child is shown two beakers: one short, squat, and half-full of water; the other tall, thin and empty. The experimenter pours the water from the short beaker into the taller beaker and asks the child which beaker had more water or are they the same. A child who does not understand the principles of conservation will claim that the taller beaker has more; a child who is able to conserve volume will recognize that the same water was in both beakers and therefore, the amount of water in both beakers was equal.