When all your slides look alike, your entire message can be blurred. At the end of your presentation, you want your audience to remember your main points most, and if they remember some of the details, that's a plus. By making key slides distinctive, you can help people follow and retain the content in your presentation. I use PowerPoint slides in some of my Web 2.0 tools by saving them as .jpegs so I can add them like pictures, for example, in Animotos.
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