Teaching by correspondence—sending instructional materials and conducting interaction through the mail—is not only the oldest and most proven form of distance education, it remains the most popular worldwide, in both developed and developing countries. As an interactive communication channel, wri tten correspondence is slower than electronic channels, but it is cheap, and in developing countries, it is usually more dependable. It is a medium that both learners and instructors are familiar with. There are benefits even in the slowness of communication, such as the opportunity it affords the learner to reflect and carefully compose a response to the instructor's questions. On the other hand, because of the possibly demotivating effect of waiting for a long time for a response to an assignment once submitted, good practice for the correspondence instructor includes the necessity of giving feedback to student's written assignments promptly.

In recent years the techniques of designing and conducting correspondence instruction have been adapted for use with new technologies.

• Jay A. Holstein, Making the Written Word "Speak": Reflections on the Teaching of Correspondence Courses

• Derek Rowntree, Promoting Active Learning