I specifically used medium instead of media here because media has come to mean different things. Media is used to describe anything from TV to floppy disks to the people who report the news. While it is the plural form of medium in its purest meaning, medium is more conclusive in the sense we are discussing. So what is medium?

A medium is an agency or intervening substance by which something is accomplished, conveyed, or transferred. For instance, when you talk on the telephone the telephone wire is the medium through which your voice and thoughts travel. In the learning process, there must be a medium through which the material can be conveyed. This can be as simple as a book or as complex as the Internet. The words and sentences in a book are the material and the book and text are the medium through which the material is conveyed. (Note: Text is not the same as words and sentences. Text is the written expression of these linguistic units of communication.)

Of course, reading a book is not a means of learning through instructional technology. The medium must be of technological composition. Let me define what I mean by a technological medium. This is any medium which uses electronic or digital products and systems. Therefore, a PBS show on cable, which facilitates learning, could be considered a technological medium.