This is when one line of text is revealed at a time while it is being discussed. Speakers are often reluctant to use this technique with slides or overhead transparencies because of the need to have many more visuals. Successive disclosure also prevents the audience from getting ahead of the speaker by being able to read points or ideas before they are expressed. Figure 1 is a good example of a word graphic that meets the criteria outlined above. If text graphics are the most common, charts are in second place.
Charts present some particular challenges.
Again, the temptation is to make the charts too complex. Since most charts consist of lines of some form, they present a special problem. Lines must be bold and thick or they face the possibility of being absorbed into one of the scanning lines that form the video signal. If a line is too thin, it may appear in only one of the two frames that make up the video signal. The result will be a flickering line that not only distracts, but also inhibits legibility.