Final answer:
A child fooled by perceptions would be in Piaget's preoperational stage. This stage is characterized by symbolic play, egocentrism, and a lack of understanding of conservation.
Step-by-step explanation:
A child who is fooled by perceptions would be in Piaget's preoperational stage, which occurs approximately from 2 to 7 years old. During the preoperational stage, children engage in symbolic play and are learning to use language, but they have not yet developed the ability to perform mental operations like adult logic or understanding of conservation; meaning they do not grasp that a transformation in an object's appearance doesn't necessarily change its fundamental properties or quantities. They also exhibit egocentrism, displaying a lack of understanding that other people have different perspectives and knowledge.
In the case described in the question—where a child is misled by appearances, such as in the scenario where Kenny thinks he has more pizza because his slice is cut into more pieces—shows a typical example of the lack of conservation understanding that is characteristic of the preoperational stage of Piaget's theory of cognitive development.