The document discusses three perspectives on learning - behaviorism, cognitivism, and constructivism. It compares their critical features from an instructional design perspective. Behaviorism views learning as changes in observable behaviors from environmental stimuli and reinforcement. Cognitivism sees learning as the processing of information, including attention, memory, and motivation. Constructivism considers learning as the active construction of knowledge by learners through experiences and reflection. The document aims to familiarize instructional designers with these perspectives to provide a foundation for designing effective instruction.