A wide range of instructional modalities and media, each serving a specific purpose, have evolved from these two basic approaches. These distance learning modalities can be loosely grouped into print, video, voice and data. Print is a foundation of distance education programs and the basis from which all other delivery systems have evolved. Textbooks, workbooks and study guides have been used for distance learning for more than 100 years. Video-based distance learning coupled with other approaches offers an excellent base for instruction.
Computers send and receive data and information electronically.
Data-related products and services appropriate for distance education are incredibly varied and resist categorization. More recently, educators have taken to using these tools as a basis for building communication environments with distant learners. Most distance educators use online forums as a cost-effective means of communicating with students enrolled in online courses. Users logon to the discussion board and type in a question, respond to an instructor's query or collaborate with other learners as part of an ongoing exchange of information. Calvert maintains an open enrollment, so that study may begin at any time of the year.