How to Determine the Reading Level of a Document

I am thinking ahead to next year and how I will use the reading tests I give my students at the beginning of the year.  Since I have technology for them all my next goal is going to differentiate for them.  I see differentiation as going two different ways: 1) learning type which I also have a test for if you look below 2) reading level.

The reading level tests are also in early posts.  But then what.  Google Documents, before it was Google Drive had a very early way to determine readability, but it is now gone.

• You can do it in Microsoft Word, but if you don't use Word 
• The easiest site to use is this one and it tells you the reading level. 
• Here is a great page that lets you insert a url and it even tells you how to calculate the level if say you are using a paper document (although in that case I would try to find it on Google books and just use the url finder).  While this site gives the scores for three reading level tests it does not tell you what approximate grade it is read at.
• Here is a way to hand calculate it for Flesch-Kincaid,  Gunning Fog Index, SMOG Index, Fry Readability Formula, and Coleman-Liau Indexs. 

So for example here is an article on Obama and his consideration of his legacy from the WashPost and here are the results for the reading levels and here is what grade it is at level 8 which means it is appropriate for 13 and 14 year olds. For comparison I entered in an article from the Economist and it said it was a reading level of 7 or could be read by 12 and 13 year old students.   The truth is that generally any article or news magazine other than scholarly articles are going to be appropriate for your high school students - unless they test below reading levels and that is where you will have to have them look up key words.  If you follow this it will also impact state exams - or at least mine which give a lot of our ESOL students problems.