Today with such mixed ability classrooms it is so important that we know if our students can engage with the text. Microsoft word allows you to check the readability of a document or if you cut and paste into word any written piece of text.
If you want to check the reading age of word documents you just have to turn on Readability statistics. Then run spell check as normal.
go to preferences
Select Spelling and grammar
Tick the bottom checkbox-Show readability statistics.
for example the passage below has active not passive sentences, has a 50 % reading ease, so not that easy, and suitable for grade level 10.9.
More about the scale used: http://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_test
Isn't it so simple. No excuses for giving a too difficult passage to students now :) Unless of course you are extending them and giving them a scaffold to analyse it.