FreeRice is a strange little game that asks you what words mean. Does rejuvenate mean bewilder, pierce, evade, or restore? As you play, it assigns you a score, the higher the better, and also tracks the number of grains of rice that will be donated to the United Nations' World Food Program.
If you get a question right, you are asked harder and harder questions. The first time I tried this, I got the first 25 words in a row correct and then missed flagitious. I noodled around for a while and my score was around 49. They say over 48 is rare. Months later, with some time to kill online, I tried it again and my score topped out around 53. Wow.
They say "FreeRice has generated enough rice to feed more than two million people since it started in October 2007" although I guess that means two million people one meal each, it's still pretty impressive. And they've added subjects like Math and Chemical Symbols, though I haven't tried those. Give it a whirl, it's fun!