The Four Levels of Access
The systems that affect access to learning can be considered as links in a chain, with the proverbial caveat that the system is only as strong as its weakest link. Elements of this access chain are outlined here. Basic explanations of the various players' roles, including those "behind the scenes," are needed in order to understand how their decisions affect educational access.

Let us begin with a fairly familiar example: print based correspondence courses introduced shortly after a postal system was established. This example demonstrates that four levels of systems must function effectively to have genuine accessibility. Firstly, there needs to be a reliable postal system (the infrastructure level); secondly, an educational provider willing to offer a course by correspondence (the institutional level); thirdly, reasonable access to a post office for the learner (the community level); and, finally, a learner whose situation permits enough time to study, light to read by, and so on (the individual level). Considering each of these levels in turn, we can examine how they relate to learning technologies, old and new.

The Infrastructure
The basic transportation and communication infrastructures established during the past century are still factors in access to learning, as well as to many other services. Those who travel to class depend on reliable transportation, whether by private car or public systems, and conditions that permit safe travel in most weather, such as well maintained roads. Those that study at a distance rely on postal or courier systems to deliver materials intact and on time, and on the telephone system to contact their instructor, the library, the bookstore and other learners.

Newer learning technologies require more from some parts of the infrastructure. For example, while the use of audio conferencing to transmit voices requires only one regular telephone line, the addition of computer generated graphics requires the addition of one or more lines, or more "bandwidth" on a telephone transmission system. Bandwidth refers to the amount of data that can be transmitted through a telephone line. Data such as letters or numbers can be sent using a narrow bandwidth while images, photographs, color, etc., require more capacity. According to A.W. Bates, "telecommunications capacity is a combination of bandwidth and speed of transmission. ⁵

Many of the newer technologies require a significant amount of bandwidth. Most videoconferencing requires transmission lines with more capacity than an ordinary telephone line, depending on the system and the quality of the image being transmitted. Computer-based material that has extensive graphics and complex structures, such as much of the material on the World Wide Web, can take a significant time to transmit depending on capacity of all the systems involved from the telephone system to the Internet provider's system, to the modem and line capacity of the user.

Another part of the infrastructure system that deserves mention is the electrical power system, which can be unreliable in parts of the country. Virtually all the new technologies require reliable and consistent electrical power.