Each of the units can be used as a standalone for self instruction, for practice or reading to get informed and reference. Each unit has an inbuilt practice exercise to help you apply what you will have covered. In addition you are called upon to measure your perceptions of the learning environment of each unit. There is cross referencing in the different units to re-emphasize issues and to avoid repetition. References for detailed reading are provided. Apart from the basics of communication of the Units (4) look at individual technologies in detail (Visual, Audio, Audiovisual and Multimedia). This includes defining the technology with examples, highlighting advantages and elaboration of practically how to use the technology in instruction.