Achild has an eight-ounce cup full of juice. while he watches, you pour the juice from the cup into a quart jar. he gets upset, because he thinks he now has less juice. the child is most likely in piaget's stage of cognitive development.

The Concrete Operative Stage

Explanation:

According to Piaget in the Concrete Operative Stage the child begins to deal with concepts such as numbers, measures and relationships. This stage comes to manifest more clearly what coincides (or should coincide) with the beginning of formal schooling, that is, with elementary school. It is characterized by consistent internal logic and the ability to solve concrete problems. In the case of the child shown in the question, we can see that she has a notion, even if very correct, of the amount of juice she had and because of that amount she worked out a reason why the amount of juice she had decreased. Because of this reasoning ability, we can conclude that this child is in the concrete operative stage.