Final answer:
During the beginning of the formal operational stage, adolescents engage in assimilation, abstract thought, and are characterized by idealism and possibilities. This stage signifies a shift from concrete to abstract thinking, where hypothetical reasoning becomes possible.
Step-by-step explanation:
According to Piaget, during the beginning of the formal operational stage, assimilation dominates, and an adolescent's thoughts are full of idealism and possibilities. The formal operational stage is the final stage in Piaget's theory of cognitive development, beginning from around age 11 and extending into adulthood. During this stage, individuals move beyond concrete thinking to become capable of abstract thought. They develop the ability to think about abstract concepts, consider multiple perspectives, engage in hypothetical and deductive reasoning, and think about the form of a problem apart from its content. Children in the formal operational stage are not limited to actual, concrete experiences as reference points, unlike their younger peers in the concrete operational stage, who think logically only about real events. Adolescents in the formal operational stage can envision multiple scenarios or possibilities that do not necessarily exist in the physical world, thus allowing for high levels of idealism and the capacity to consider hypothetical situations and solutions.