I homeschool, so this site is very handy for my mom. I do it a bit, but in the English section. I have gotten up to 2,160 at a time, I think.
I e-mailed my friend about this, and she e-mailed back saying it was a very fun site!
I think it's a cool idea to abolish world hunger and learn at the same time.
My One Quirk About It Though: With the English section (or at least this has been my exprience), they repeat the words. sure, they sprinkle a decent amount of new ones in every time, but now I don't do it as much as I did the month I saw it.