In case you haven’t heard of Freerice.com you should check it out.
About Freerice.com:
Freerice is a non-profit website that is owned by and supports the United Nations World Food Programme.
Freerice has two goals:
- Provide education to everyone for free.
- Help end world hunger by providing rice to hungry people for free.
Also, it’s not just English vocabulary anymore: you can select from the following subjetcs:
HUMANITIES
MATH
LANGUAGE LEARNING
SCIENCES
ENGLISH
CHEMISTRY
GEOGRAPHY
TEST PREPARATION
John Trendler: Still Learning 