Please try this fun website: Free Rice which is the sister site of Poverty.com.
You will be given a word and a choice of 4 definitions... choose the definition which most closely fits the given word. For each correct word, 20 grains of rice are donated to the United Nations World Food Program. You can play for as long as you like and as often as you wish so there will be the added benefit of improving your vocabulary. There are 55 vocabulary levels although the website says that 48 is normally the highest level attained... I have managed to reached level 46 (without cheating).
It's a cool website that really does donate rice to the UN program and this is achieved through advertising revenue. Read more in the site FAQ.
Have fun and let me know how you do!