Answer:
Liquid conservation
Step-by-step explanation:
Jean Piaget proposed, as part of his cognitive development theory, that around ages 7 to 11, children develop the idea of "conservation"
This concept refers to the thinking ability that allows a person to know that a certain quantity of liquid or mass will remain the same despite being changed of container, shape, or apparent size.
In this example, Rochelle has a glass of Kool-Aid, she pours it into a different container (a teacup) and then into a beer stein and then into the original glass. Younger children would think that the teacup has less liquid (since it's smaller) and that a significant amount of liquid is lost while doing all this changes from recipient to recipient.
However, Rochelle knows that this quantity of Kool-Aid remained the same despite being changed of container, thus, this is an example of liquid conservation.