The document discusses three approaches to educational technology: hardware, software, and systems. The hardware approach focuses on using physical devices and equipment to aid teaching and learning. The software approach applies principles of psychology and behavioral science to modify learning. The systems approach views education as a system and provides a systematic way to design an effective and economical educational system through setting goals, analyzing resources, devising plans, and continuous evaluation. Instructional development is also discussed as a systems approach that applies scientific principles to plan, design, create, implement and evaluate effective instruction.