JoGo Green is the latest in a series of cause-related games that make charitable contributions based on the number of questions answered correctly by players. This, of course, was all started by the famous Free Rice vocabulary game.
With JoGo Green, money is contributed to an organization that plants trees. The amount is based on the number of correct answers you give to environmental-related questions — many which would be accessible to high Intermediate and Advanced English Language Learners.
One thing I do have to say is that of all the Free Rice imitators, JoGo Green clearly goes farther than any of them to demonstrate proof on their website that they are actually donating the money. Apart from FreeRice, I can’t say with much certainty that the others are legitimate.
I’ve placed the link on my website under Toward The Twenty-First Century.