Build a readability index
Perl 120 bytes

#!perl -pa0
s@\w+|([.!?])@$s+=$#-,lc($&amp;)=~s![aeiou]+\B|([aeiouy]$)!$y+=1-$#-/3!ger@ge}
{$_=206.835-1.015*@F/$s-84.6*$y/@F


Sample I/O:

$ perl flesch-kincaid.pl &lt; input1.dat
110.730040322581

$ perl flesch-kincaid.pl &lt; input2.dat
65.6097727272728

$ perl flesch-kincaid.pl &lt; input2.dat
1.71366197183096


Counting of syllables is done by assuming that each vowel cluster is a single syllable, except for lone vowels at the end of a word, which are only counted two thirds of the time; a heuristic that seems to be fairly accurate.