How could we apply Piaget's cognitive theory of 'preoperational thought' to understand a preschooler's thinking and behaviour?

How could we apply Piaget's cognitive theory of 'preoperational thought' to understand a preschooler's thinking and behaviour? Please provide a detailed description of the different thinking processes (egocentrism, etc.) during this stage of development, as well as a concrete example.  Be sure to interpret the example according to Piaget's theory of preoperational thought.