There’s a specific, measurable reason a crowded slide works against you, and it isn’t that text on screen is bad in itself. Research on narrated explanations found that showing the same words on screen while narrating them improved comprehension when nothing else was competing visually — but the moment an animation or a diagram shared the screen, that same text stopped helping and started actively hurting. The words and the graphic fight over the same visual working memory, while your voice runs on a separate auditory channel (Moreno & Mayer, 2002).
A board slide with a chart and a paragraph of commentary asks the room’s eyes to do two jobs at once, and the eyes lose. Cut the paragraph, keep the chart, and say the paragraph out loud instead — your voice isn’t competing with the chart, it’s the one channel that’s still free.
Try this now. Take your densest slide and count the things on it competing for attention at once: a chart, a headline, body text, a callout box. Cut it down to the one visual that matters, and move everything you were going to read off the slide into what you actually say out loud.
The test for a good slide in this course isn’t whether it looks complete on its own. It’s whether it would still make sense to someone who could see it but not hear you — if the answer is yes, it’s probably carrying more than it needs to.
