Readability
http://www.impact-information.com/impactinfo/fryreadability.pdf

Fry, Edward
Impact Information
2006

Abstract:

I know from some years running a reading clinic in the United States that you can make more progress if you start the students out on relatively easy reading material so the the students can read the materials with some comprehension and success. But how do you tell these African instructors how to select “relatively easy” reading materials in technical English? The answer - use a readability formula.