I could also play a preselected song, or a laser disc, CD-ROM, or even a digitized video. These features all help to illustrate the points I'm making in the lecture. Maps, charts, photos, music, and action are available literally at the click of a button. They give concreteness to abstract concepts and show students what I'm trying to describe. The downside to this process is that creating these stacks prior to class is time-consuming.
Text has to be typed in.
Those video portions which are to be used have to be preprogrammed, as does the music. Clip art has to be sought out and placed. Buttons have to be created. The upside, however, is tremendous. In addition to the more theoretical advantages mentioned, there are some very practical ones.