Slides with lots of text on them are hard for audiences to comprehend quickly. There’s just too much information. Either people listen to the presenter and ignore the slide, or more likely (and worse), they read the slide and ignore the presenter.
The brain simply has difficulty listening to one set of words while reading another set. Also, studies show that people tend to skim what they read on screen (as opposed to what they read on paper); therefore, they miss many of the words.
The best solution is to put fewer words on a slide. It’s easy to divide one slide into three, for example. Another important technique is to edit ruthlessly, removing any unnecessary words.
However, if you feel that you need to put a lot of text on a slide, you can help your audience get the most out of it by making key words stand out. Here are two techniques to highlight important words.
Use a different color for key words
An easy technique is to use a different color for key words. People quickly get the point by skimming these words. Simply select the key words and choose another color by clicking the Font Color button on the on the mini toolbar or the Home tab.

different color for key words
Animate a filled rectangle behind the words
Another method is to use custom animation to display a filled rectangle behind the key words. Follow these steps:
- Choose Insert tab> Shapes> Rectangle.
- Drag across some key words to cover them with the rectangle.
- Remove the outline. To remove the outline, on the Format tab, use the Shape Outline button in the Shape Styles group, and choose No Outline.
- Specify the fill of the rectangle. The color needs to be a strong contrast from the text, yet show up against the background. Use the Shape Fill button and choose an appropriate color.
- Choose Animations> Custom Animation in PowerPoint 2007. In 2010 and later click the Animations tab.
- Choose Add Effect or Add Animation> Entrance> Wipe. You can choose any entrance animation you want, but keep it mild. A Fade animation is also nice.
- Set the parameters for the animation at the top of the Custom Animation task pane or from the ribbon’s Effect Options drop-down list. For Wipe, set it to wipe From Left. I used Fast for the Speed setting. I left the On Click setting so that I could control the timing as I was speaking.
- Right-click the rectangle, and choose Send to Back.
- Test the animation in Slide Show view. Here you see the result after 2 clicks.


For highlighting another way is to select the text you want, go to Format, and click on text effects. Then click on glow and pick the colour..
or
[IMG]http://i43.tinypic.com/2wr2cfo.png[/IMG]
That’s a good point about not being a workaround for having too much text on the slide.
Here’s a 3-minute video showing how to use a 3rd method, which puts a yellow background on the text (like you can in Word). As with your first method, the advantage is that when you edit or move the text, the formatting stays with it.