In a recent lecture I attended, I heard the professor say the following as he advanced to the next slide in his PowerPoint, "So what this slide talks about is..."I thought nothing of it for a moment. I've heard people make the same comment many times in lectures, pitches, etc. As I looked at the slide, I thought if this slide could speak it would sound like a lot like a socially-inept scientist with an agile mind and free tongue! In other words: utterly incomprehensible. I sat patiently and hoped that the professor would translate the slide into English.
If you have to explain what a slide 'says' then something is wrong with the way it is designed.
Slides do not talk. You do. Slides cannot teach, they can only help you teach.
Design your slides to follow what you would naturally say and to help illustrate complex or abstract ideas. Don't use slides as your lecture notes. Take advantage of (but don't overuse) slide transitions and animations to show the main idea and then progressively reveal the details as you talk about them.