Free Rice Review

I am currently a teacher that insists that my classes mutli-task.  We are moving at different paces in my class and once the general part of the lesson is complete students may be doing many different things.  In my research for another project, I stumbled across a teacher that used this site as work for early finishers.  It has a three-fold reward.  The students can feel like they are playing a game, the website is compeletely educational and the students are unwittingly doing something good for someone else.  How can that be a bad thing?!?  Students will compete to see who can get the most consectutive grains of rice.  It's something fun and educational for the students.  The only down side is that for some of the categories the game is over too soon.  Some categories only have one or two levels and it's very easy to finish them and get bored.  Other than that it is a great site and I love it.