The Yahoo Answers service has over 400 million answers to user generated queries indexed. Unfortunately, many of those answers are wrong. Schools really don’t need to spend any time worrying about 9th graders outsourcing their homework to Yahoo Answers. Odds are the kids that try that won’t do so well.
Where Wikipedia is a community edited encyclopedia, Yahoo Answers is the internet equivalent of asking 25 random strangers on the street for a restaurant recommendation, or medical advice. Even if you are getting great information, you won’t know it until after the fact. With no trust or reputation system in place, the advice is of limited value because you have no way to know if the person providing advice is qualified to do so. Your question may get 75 answers, ranging from truly insightful to just plain wrong. If you knew enough to sort the wheat from the chaff, you probably wouldn’t be asking in the first place.
If your kid is using Yahoo Answers as a research source, you may want to have a chat.