Play a word game & help the world hunger in the process

I really like this site FreeRice.com that I have come across while visiting the World Food Programme site. Here is a screenshot of the site:

Great way to engage people and in the process help end the world hunger. Very clean and intuitive design and layout. Every word you get it right, the site donates 20 grains of rice to the World Food Prgramme through the help of site sponsors. If you miss a word, it will tell you the correct meaning and will ask you again later to see if you get it right this time. It will keep asking you the word until you get it right. Excellent way to learn vocabulary and you could also set the level where you want to start practicing by going into the options page. And as you progress through more and more words, it will keep moving up the level and if you want to start at the base level again, you simply click on the Home button. Enjoy learning new vocabulary and help the world hunger in the process. Sonny