In part to justify, and in part to explain the phenomenon, theoreticians like Holmberg, Keegan and Rumble explored the underlying assumptions of what it is that makes distance education different from traditional education. In order to justify the importance of this non-traditional kind of education, early theoretical approaches attempted to define the important and unique attributes of distance education. Using the post-industrial model, Keegan presents these three approaches to the study and development of the academic discipline of distance education. It is this concept of industrialized, open, non-traditional learning which, Keegan says, will change the practice of education . Meaningful learning, which anchors new learning matter in the cognitive structures, not rote learning, is the centre of interest.
Teaching is taken to mean facilitation of learning.
Recently, a wider range of theoretical notions have provided a richer understanding of the learner at a distance. Four such concepts are transactional distance, interaction, learner control and social presence. This distance is determined by the amount of dialog which occurs between the learner and the instructor, and the amount of structure which exists in the design of the course. Greater transactional distance occurs when an educational program has more structure and less student-teacher dialogue, as might be found in some traditional distance education courses. Education offers a continuum of transactions from less distant, where there is greater interaction and less structure, to more distant where there may be less interaction and more structure.