Media Defined
Media can be defined by their technology, their symbol systems, and their processing capabilities. The most obvious characteristic of a medium is its technology, the mechanical and electronic aspects that determine its function and to some extent its shape and other physical features. These are the characteristics that are commonly used to classify a medium as a "television," a "radio," and so on. The cognitive effects of these characteristics, if any, are usually indirect. Characteristics such as size, shape, and weight makes it more likely that a student will learn with a book while on a bus but not a computer, though of course this is changing as computers get smaller, lighter, and cheaper. On the other hand, some cognitive effects of technology are more direct. For example, the size and resolution of many computer screens is such that reading text may be more difficult than it is with books (Haas, 1989).