Clark, R.C. & Mayer, R.E. (2011). e-Learning and the Science of Instruction: Proven Guidelines for Consumers and Designers of Multimedia Learning. San Francisco: Pfeiffer. 3rd Edition.
If you're looking for a "textbook" on online learning, this is it. It is a comprehensive guide to best practices based on research, experience and practical examples of focused and effective online learning. It is in strong demand for those becoming instructional designers and is on the shelf of all who practice this work for a living. Why? Because it is evidence based and very focused. The authors use a set of principles to shape their approach and they practice what they preach. None of the approaches or suggestions here are made up or guessed at - it is a science based approach to learning design. Some think of this as the instructional design bible.
