Cognitivism focuses on mental processes like thinking, learning, problem solving and attention. It became a dominant theory in psychology in the 1960s, replacing behaviorism. Robert Gagne was a prominent cognitive psychologist who developed learning theories based on behaviorism and information processing. He identified five categories of learning and nine events of instruction to maximize learning internally. Applying cognitivism in a classroom would involve determining student learning levels, shaping instruction accordingly, and using different activities and assessments.