22. Two closed, pyramid-shaped beakers containing clearly identical amounts of a liquid are judged by a child to hold different amounts after one of the beakers is inverted. The child apparently lacks a sense of what child development milestone?

b. Concept of conservation  

Explanation:

The concept of conservation is related to logical ability. This is the ability to understand the logical thinking that a certain quantity is the same despite the size has been changed. It helps a person to understand the shape and size, and apparent size.

The concept of conservation was given by Jean Piaget. The conservation is not found in the pre-operational stage of development in children. Conservation is a property of children in which children developed logical thinking about the invariant size, shape of an object despite it is not resent in front of a child.  

Thus in the above statement, the child lacks the sense of what child development milestone.