Sally's choice illustrates Piaget's concept of "conservation".
Conservation is one of Piaget's developmental achievements, in which the child comprehends that changing the type of a substance or question does not change its sum, generally speaking volume, or mass. This achievement happens amid the operational phase of advancement between ages 7 and 11. You can frequently observe the absence of protection in kids when there are, for instance, a few unique sizes of juice on a table, and they pick the glass that is the tallest in light of the fact that they see the taller glass as having more squeeze within it (despite the fact that the tallest glass may likewise be the most slender). Every one of the glasses may have a similar measure of juice in them, yet youngsters who haven't refined preservation will see the tall glass as being generally full.
