Few days ago, I heard this site from Steve Hoca. While this site enables to refresh and develop your vocabulary knowledge, it is non-profit websites and ıt helps people who need food and education. I think about this site, it can be effective as a part of English teaching. For example, as teachers we can ask our students to visit this site and work on vocabulary test and each day individually work on ten words etc.And as a result of collecting rice, this site can be competitive for our students and with making small groups from class members also we can make cooperative learning atmosphere too.
By the way, in this sites, there are different kinds of subject too. Such as geography, art, maths, and other languages etc.
Enjoy while you are supporting helpless people.
You can reach on free rice