separation of teacher and learner in time or place, or in both time and place

institutional accreditation; that is, learning is accredited or certified by some institution or agency. This type of learning is distinct from learning through your own effort without the official recognition of a learning institution

use of mixed-media courseware, including print, radio and television broadcasts, video and audio cassettes, computer-based learning and telecommunications. Courseware tends to be pre-tested and validated before use

two-way communication allows learners and tutors to interact as distinguished from the passive receipt of broadcast signals. Communication can be synchronous or asynchronous

possibility of face-to-face meetings for tutorials, learner–learner interaction, library study and laboratory or practice sessions; and

use of industrialised processes; that is, in large-scale open and distance learning operations, labour is divided and tasks are assigned to various staff who work together in course development teams.