We’ve all seen lots of student and adult-created very bad slides.
Here are some resources I’ve used to help teach students to improve their quality (You might also be interested in The Best Sources Of Advice For Making Good Presentations):
I’m going to start off with a slideshow that Katie Hull Sypnieski and I use with our classes use the Concept Attainment instructional strategy (see The Best Resources About Inductive Learning & Teaching). We explain the lesson in detail in our upcoming book on teaching English Language Learners, which will be out next March:
Dodging Bullets In Presentations is a useful slideshow to review.
PowerPoint Hell: Don’t Let This Happen to Your Next Presentation also comes from PC World.