The document describes Piaget's theory of formal operational stage of cognitive development. It begins around age 11 and lasts into adulthood. During this stage, adolescents can think abstractly and hypothetically without relying on concrete experiences. There are two phases - the early operation stage where abstract thought, logic, metacognition and hypothetical reasoning emerge, and the late operation stage where skills are mastered more quickly and at higher levels, including understanding religious symbolism and establishing scientific problem-solving plans.