Is the change of your free wiki to an also free , but "educational one" (for schools, universities, students , teachers) with better, practical, conditions. You will find it in the dashboard of your site manager ( page _admin ) of your free wiki. Be carefull - upgrade to a pro account can stop some conditions! See http://www.wikidot.com/education!
Wikidot is used by many teachers or students in free , but often private, wikis with a special status: "educational" - which goves some good conditions for free wikis but only for such wikis used by universities or schools (will be checked at the upgrade).
You will find these conditions on the dashboard of your site manager on your fre wiki and also the "educational upgrade" button with some fields to fill in ( like school/universities email/link a.s.o.).
See also http://www.wikidot.com/education
But a warning: if you are using such free educational wiki you can loose some good conditions if you upgrade later to a pro light / pro account and have perhaps less conditions as before on your upgraded pro-wiki than.