Tyler used his understanding of conservation to end Max's tantrum.
Explanation:
Max is only three years old, not yet able to understand that, even though the appearance of the cookie changed, the amount of cookies he has is the same as before. That ability is called conservation, according to Piaget's theory. Tyler knows that Max hasn't developed conservation yet, so he tricks him into thinking he has two cookies, so to speak, instead of just one. Of course, once he develops the ability to understand conservation, Max will no longer be fooled.
