Introduction
By following a few basic rules, you can produce legible computer/projection-based "slide-shows."

PowerPoint simplifies slide production. It's easy to cut-and-paste text from existing paper handouts, choose a colorful PowerPoint template, and put one slide after another.

However, most instructors are accustomed to the print-and-paper medium rather than to the pixel-and-light medium of the computer.

PowerPoint was designed as a sales-presentation tool, and you aren't selling anything. So pay attention to the communicative functions in your presentation rather than the "sizzle." Legibility, clarity and brevity are what matter.
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In a Wired article entitled "PowerPoint is Evil," Edward R. Tufte, professor emeritus of political science, computer science and statistics, and graphic design at Yale writes:

"At a minimum, a presentation format should do no harm. Yet the PowerPoint style routinely disrupts, dominates, and trivializes content. Thus PowerPoint presentations too often resemble a school play -very loud, very slow, and very simple.

The practical conclusions are clear. PowerPoint is a competent slide manager and projector. But rather than supplementing a presentation, it has become a substitute for it. Such misuse ignores the most important rule of speaking: Respect your audience".

Follow the suggestions below to do just that!

1. Contrast matters

The greater the contrast between the color of the text and the color of the background, the better the legibility.

In figure 1, the dark red title and black body text stand out in contrast against the white background.

More on color and contrast for text on the computer screen.

2. Avoid white text

Dark backgrounds tend to "flood" light-colored text, making the letters look smaller and fainter, and making text harder to read.

A lot of light-colored text on a dark background can be tiring to read.

More on type and background color.

3. Use color wisely

Avoid using more than 3 colors for text in a presentation.

For example, If you use black body text on a white background, use red for emphasis, and blue for hyperlinks.

Remember that some viewers may be color blind. More on accessibility issues.

5. Use a screen font

Verdana, Arial and Georgia are "screen-fonts" designed for reading text from a omputer screen. When you use them, the letters remain legible when a computer screen is projected.

Times is designed for reading from paper. and is hard to read on screen.

Times "New Roman" has been adapted to make it more screen-friendly, but it is a poor choice.

Titles should be at least 32 points; body text should be at least 24 points.

Use the following guide: use one inch of letter height on screen for every 30 feet of viewing distance from the last seat to the screen (for example, this is 60 feet in the large room in Lakeview).

Check the legibility of your presentation from the last row of seats where you'll present. If you can't visit the room, ask for room dimensions

The PowerPoint default title screen uses a 44 point font-size for the title, and 32 points for the text. You can decrease these sizes somewhat for the rest of the slides.

People read words in all caps more slowly than they do words in title case or regular sentence case.

Italics are poorly rendered on screen. Computer screens use square areas of light (pixels) to display letters on screen.

Square pixels are not suited to the exaggerated curves of italics.

8. Limit information per slide.

Use no more than 6-7 words per line, or about one-and-a-half alphabets, and 5-6 lines of text per page.

Some people suggest the "7X7" rule -use no more than 7 words per line and 7 lines per slide. I think this is too much for 1 slide.

Do you really need bullets when you provide visual cues like indents and a new text line for new information?

9. Don't rush

Give people time to read and mentally process each new slide.

Pause, stand still and mentally count to five after you put up a new slide.

If you speak or move immediately, your audience may still be reading and not listening to you.

And of course, you know not to stand in front of your show!

10. Write for the medium.

When writing text for slides, be succinct. Write, prune, re-write and prune again. (For general suggestions about writing for screen reading,see Writing for the Web, by Jakob Neilsen.)

When you are already providing visual cues like indents and new lines for new information, do you really need bullets?

Avoid text "zoom" effects, where a line "floats" onto the page. You aren't at a sales meeting here...

11. Don't print a copy

If you follow the suggestions above, you'll give a clear and legible presentation.

If you give your audience a paper copy of each slide, which is (too) easy to do in PowerPoint, they will get a document you have carefully designed for screen reading rather than for print reading.

If you want your audience to read your presentation text, then make a print version designed for reading from paper.

And finally...

For a recap of the points above, check out this great PowerPoint slide show (it's a PowerPoint about Powerpoint) by Dana Pergrem and used in her Communications class.

Dana Pergrem has also produced a "How-To" which shows basic steps to using PowerPoint.