apostrophe not recognized in lesson shortanswer question
see http://moodle.org/mod/forum/discuss.php?d=168052

easy fix:
in file lesson/pagetypes/shortanswer.php
around line 80
replace:
foreach ($answers as $answer) {
$i++;
$expectedanswer = $answer->answer; // for easier handling of $answer->answer

with

foreach ($answers as $answer) {
$i++;
$expectedanswer = s($answer->answer); // for easier handling of $answer->answer