I recently heard about a really cool site, called freerice.com.  I'm surprised that I didn't hear of it before, because I think it started in 2007.   It is kind of a small-ish website with several academic style quizzes and multiple choice answers.  Why bother, when there are much cooler sites with better graphics and more challenging games?  Because for every correct answer you give, they'll donate 10 grains of rice. I just worked up to 1000 grains total, and I'm sure I'll be back.