Conservation is the understanding that a given physical quantity does not change despite superficial changes in its appearance. Preoperational children lack an understanding of conservation. Lacks Reversibility Children in the preoperational stage of reasoning lack an understanding of reversibility. They do not understand that an action can be done and then undone. It is not until the age of 6 or 7 that children progress to the next stage of cognitive development, the concrete operational stage, when their thinking skills progress beyond these limitations.
Children develop at their own pace.
Challenge the child's abilities, but do not present material or information that is too far beyond his or her level. There are some tasks or ideas that children will not be ready to understand until they progress to a certain point in development, and that's normal and healthy. Topics covered include psychology, development, writing, health, parenting, and personal growth. Piaget's theory Excellent article, Tara. You made a complicated body of work very easy to understand.