readability and grade level

The "reading level" or "grade level" of text is an interesting idea.
Take a look at the table "Grade Level and Circulation of Current
Periodicals" in

http://www.impact-information.com/impactinfo/newsletter/plwork15.htm

The "grade level" numbers refer to US school years, so 12 = last year of
high school, 16 = last year of college.

Microsoft Word will compute readability scores for you. This article
about website accessibility describes some of the pluses and minues of
the MS Word readability function.

http://www.wats.ca/resources/determiningreadability/1