Sometimes an idea is difficult for an audience because its complexity makes its main points—the “big picture”—hard to grasp. In this case, speakers should use a quasi-scientific explanation. Just as scientists try to develop models of the world, quasi-scientific explanations provide a model or picture of the key dimensions of some phenomenon for a particular audience. These explanations work particularly well for speakers presenting complex topics to laypeople, such as how microchips work, the similarities and differences between levees and dams, or how DNA molecules pass along genetic information. We heard a particularly good quasi-scientific speech explanation in which the speaker explained how radar worked by comparing it to the way an echo works, except that it involves radio waves rather than sound waves.

Effective quasi-scientific explanations highlight the main points with such features as titles, organizing analogies, presentation aids, and signposts (“The first key point is . . .”). Good quasi-scientific explanations also connect key points by using transitional phrases (such as “for example”), connectives (“because”), and diagrams depicting relationships among parts.