As of November 2011, all course content created by Productive Learning's employees shall be checked against the Flesch Kincaid readability formula and the FOG index prior to external consumption. Existant content shall be checked, evaluated, and re-written if needed prior to the start of the 2012 school year.

Internal testing revealed that the Flesch Kincaid method tends to guess a little low and the FOG index tends to guess a little high. Both methods look at the average number of words per sentence and the average number of syllables per word. They then estimate the grade level of the reading. One weakness is that common words in the English language are treated the same as uncommon words of the size and syllables. They also do not cross-reference grade level vocabulary lists. Because of these limitations, readability formulas work best when teachers and course developers compare other content of known difficulty against the same metrics.

Readability formulas are useful, but in the end, it is the responsibility of teachers and course developers for to keep the reading level of materials produced appropriate for the grade level of intended users.

Technical note:

Openoffice has two modules for calculating readability levels: Readability Report and Linguist. The first calculates the Flesch Easy Reading Formula, the Flesch Kincaid Formula, the FOG Index, the SMOG Index, the Automated Readability Index, and a weirdness metric. The second provides a lix readability score.