Step 1: Understand that Piaget's Cognitive Developmental Theory outlines four main stages through which children progress as their thinking develops.
Step 2: Identify the first stage as the Sensorimotor stage, which occurs from birth to about 2 years old, where infants learn through sensory experiences and motor actions.
Step 3: Recognize the second stage as the Preoperational stage, typically from ages 2 to 7, characterized by symbolic thinking and egocentrism but limited logical reasoning.
Step 4: Note the third stage is the Concrete Operational stage, from about 7 to 11 years old, where children begin to think logically about concrete events and understand conservation.
Step 5: Finally, the fourth stage is the Formal Operational stage, starting around age 12 and continuing into adulthood, where abstract and hypothetical thinking develops.