As long as you have an electrical outlet and the right equipment, overhead transparencies are a simple way to add a little tech to your presentation. The order of presentation can be quickly changed should you decide to take your speech in a different direction after talking with members of the audience before you start or as you present. Transparencies can be seen by a large crowd. And you can add notes to the edges to remind you what needs to be said in the narration.
Compared with slides, videos, and software presentations, overhead projectors are readily available. They can also be shown in fully lighted halls, so you do not risk having to turn lights down and have people doze. And you can mark up transparencies during the presentation to emphasize points or in response to questions. However, they often cannot be seen as well in the back of a large room, so ask in advance about the dimensions of the screen and room.
Use a white piece of paper to mask the writing on transparencies before you talk about each line, lest the audience read the whole sheet while you are still narrating the first point.
Because overheads are static, you might think they have less ability to convey the information effectively to audiences. In fact, despite the drive for ever-more sophisticated presentation technology, studies have shown that there is no less learning advantage to using overhead transparencies compared with 35mm slides or PowerPoint.