To the eye your presentation will give information about shapes, colors, surface qualities, and spatial relationships. To the ear, your presentation will provide reasoning. The best technical talk is an effective mix of verbal and visual elements. Illustrate what you cannot verbalize, what would take too long to describe, or what you want to emphasize. Use slides to hold attention, illustrate, clarify, restate, explain and interpret.
Ears have trouble accepting numbers and abstractions.
Numbers are easier to remember if they are written out. Quantities and relationships must be visually compared. By adding illustrations to your spoken words, you add understanding to what you are saying and enliven interest in your presentation. Animations Make use of its dynamic capabilities to highlight different features, to indicate a chain of reasoning, to introduce successive levels of detail into an example, or to demonstrate the dynamic behavior of an algorithm. Maintain context Never say one thing visually on the screen and something else orally.