I have heard of this, but never really looked at it till recently. Free Rice is a website where people can answer simple multiple choice questions and for each one that is right, 10 grains of rice will be donated to help feed the hungry. Questions get easier if you get it wrong and get harder if you get it right. You can choose from various subjects, including Geography, English Vocabulary, Mathematics, Foreign Language, Chemistry, and Humanities.
Students can create an account and track their progress (under 14 requests a parent email). This would be a great way to provide extra credit based on number correct or number in a row correct. Teachers can create groups as well and students can join them. Have a rival school? Create a group for each school and see who can get the most grains of rice donated; would be a great homecoming activity and good publicity.
Have extra time in the computer lab? Have students answer questions and help fee the hungry at the same time. Imagine the impact if every teacher would do this across the country every time the opportunity presented itself.
You can follow Free Rice on Facebook as well.