In the research arena, it seems that instructional designer after instructional designer is devising his/her own ID theory.  However, practitioners are overwhelmed by the vast number of them and unsure of how and when to use them.  So far, my experience with instructional design and learning has been through the “practical” application as an educator.  While many educators have had exposure to different types of instruction and learning theories, I do not truly believe that most educators have a firm grasp on what an ID theory is.  We go about our teaching duties using one teaching style or another and overtly or covertly using one learning theory or another.  But ask us to define our theory of instruction or how we design instruction, we are at a loss.  Even the best, well informed educators might have a hard time deciding what is the best ID theory for their students or adequately distinguishing one theory from another. 

            Much of the confusion comes from the ever-changing nature of these theories, the small sometimes-indistinguishable differences between many of them, and the fuzzy use of labels, terms and concepts in the theories. So why and how are there so many differences between instructional design theories, why do they change, and how do these changes relate to the theories and approaches that promote understanding through instruction?