Cramster.com - Get help with math and science homework

Struggling with that chemistry assignment? Maybe you've even tried visiting your professor after class, or hiring a tutor, and still you need help. Take a look at Cramster.com, a user submission site that lets people ask and answer questions related to studying Physics, Math, Science, and Engineering. You just have to register for free to participate. When you ask a question in one of the forums, another user will answer it, and then you provide feedback to that user saying whether the answer was helpful or not. Once a person has answered a few questions successfully, he begins accumulating points which can be used for Rewards. The Rewards are goodies like t-shirts and gift cards to Amazon.com, Starbucks, and Barnes and Nobles. This system ensures the answers will be at least somewhat helpful. Whether they are correct or not is hard to know! In addition, Cramster provides thousands of lecture notes, study tips, and practice exams.

"Get help. Understand it. Be prepared. Find homework solutions, lecture notes and practice exams for your actual textbook. Find textbook answers explained! Easily ask any problem. Submit your solution for rewards. A Study Community for Physics, Math, Chemistry and Engineering Help."

Cramster provides many useful tools that will aid high school and college students with specific assignments as well as general study habits. It's like an open online tutoring system. It's free and easy to use.

Is there any way students actually know if the answers are correct? Does the site want people to give negative ratings if the answers are incorrect?