Answer:
conservation
Explanation:
The third stage of Piaget's theory of cognitive development deals with the development of logical thought. It is concerned with middle childhood that falls between the age of & to 11 where children understand the concept of conservationism. It means that a child understands that changing the form of an object does not affect its amount, mass or volume.
As per the question, Ava does not understand the concept of conservatism.