Witg both filmstrip and sildes the teacher must prepare himself and the class and the equipment must be checked in the advance. An effective follow-up is also necessary, and this can take the form of a discussion or a test followed by another showing.
There are obviously occasions when sound or music may be necessary as a background or as an essential part of slide presentation. The simplest method of achieving this is to record the proposed track on tape while projecting the slides at a suitable rate, preferably using a magazine projector with remote control. The recorded commentary can have cues in the appropriate places. For more elaborate and sophisticated presentation a special device can be fitted to the tape. These are applied to, and on replay picked up from, the second track of the tape. The same procedures can be adopted for filmstrip projection. Many such filmstrips are now available.
Slide and filmstrip projectors must have sufficient power, which for a normal classroom is 750-1000 watts. In addition to the power of the lamp the quality of the lenses and reflectors is important in obtaining a brilliant image.