My Take
This website is a great filler resource. My students love earning rice for hungry children while they increase their vocabulary. The site self-regulates the difficultly of questions based on correct/incorrect responses.
How I Use It
I use Free Rice as a filler activity for students who are finished with their computer work. It's easy for them to get into the site and begin earning rice.
You can create a log in to track specific class counts. I've used it to track rice counts and reward certain classes.