Save the rainforests

In the tradition of FreeRice.com comes OneSquareFoot.org, a site that offers to save a square foot of rainforest land for every nine trivia questions you answer correctly.

Some of the questions are really freakin' hard, which doesn't seem fair to the rainforest. (Such as: What is the result of a dot product of two vectors? A: Hell if I know!) But, it's a good time waster with a beneficial consequence.