Here is yet another site I came across . Not sure if it was mentioned as of yet? Here it is http://www.purposegames.com/games for quick navigation look to the left for subject areas 
Have fun…
Susan Khan
PS for you geography lovers here is one more http://geographyworldonline.com/
GREAT! Karma to you!! Only one question about the first link: If you cannot find the correct answers trying three times it suggest you use the “hint” function - anybode knows where that is?
Hi, Im not sure where that option is?
Yeah, they didn´t really mark that function clearly, that much is for sure! javascript:void(0)
Thanks. Let´s see if anybody else knows.