According to piaget,
is a belief that objects continue to possess physical attributes (such as volume) despite superficial changes.

Conservation in the cognitive-developmental stage of children in psychology

Explanation:

Conservation is part of the third stage. This is the phenomena children cognitive development stage introduced by psychologist Jean Piaget. This stage is existing between the age of seven to eleven years. In this stage, children start to thinking rationally and to understand the organizational phenomena of things. The concrete stage has a major contribution to childhood cognitive development. At this stage, children start to use logical phenomena on solid or physical things. Children start such of development in this stage:

Conservation: Number, volume, area, and orientation, etc.  

Reversibility, serialization, decentralization, transitivity, and classification all are the key points of concrete development.  

Conservation is related to understand that things are present in the same number, area, volume, and quantity even its being changed in appearance.

they could find out our specific needs.