I have received several questions from people about how to create reading rulers (sometimes called transparencies). Reading rulers are often immensely helpful to students with dyslexia because they reduce the sharp contrast of black text on a white background and they help the student track the text. They can mean the difference between the ability and inability to read.
To create a reading ruler, you need to have transparency films. It is easiest to use printer-friendly transparency film (this is a good example http://www.staples.com/Staples-100-Pack-Transparency-Copy-Film/product_368095 but any similar product will work).
Then you can create several rectangles approximately the length and height of a line of text in Microsoft Word. Set each rectangle to a different color. Finally, add an arrow to the bottom of the rectangle that points in the direction of the text. Keep in mind that the colors will be much lighter than they appear. I have created this example for anyone creating their own reading rulers: https://docs.google.com/document/d/1W2a2jHCmLe7UnbaLQM2O2qwQmEM-ngSgj1ZTbZ0MJYU/edit?usp=sharing