Quora

Teens can get basic reading practice and some research experience. Observing ongoing debates about the validity of some posts will hopefully help them understand the difference between substantiated and unsubstantiated facts. The site's brief tips on writing questions and responses can also help teens understand other language principles, including sentence structure and brevity. Being able to communicate questions and receive multiple responses also encourages collaborative group learning, self-expression, and intellectual curiosity.

However, educators will likely have some concerns about teens accessing some of the site's less kid-friendly content. Users post questions on a variety of topics, ranging from crime to sexual acts, and many responses are clearly intended for adults. Plus, there's no guarantee that kids will receive plentiful, or even accurate, responses to their questions. The system relies on users to provide answers but doesn't authenticate or confirm their level of expertise on the topic. Quora lists entrepreneurs, CEOs, journalists, and other professionals -- reportedly from reputable sources like the BBC and AOL -- as users who have contributed to the site. But there's really no way to tell if all profiles are legit. Users also essentially rank comments by designating ones they like with an upvote, which doesn't necessarily indicate if the response was thorough or needed more work.