We'll create fresh WordPress site with tas2580 Readability Index installed. You have 20 minutes to test the plugin after that site we'll be deleted.
This Plugin calculates the Flesch readability index for the content of an article and displays it at the bottom of the article.
For more information about the Flesch readability index see: https://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_tests