In 2007 I read quite a few articles on the topic of libraries and educational institutions banning the use of Wikipedia. Many of them on the grounds that Wikipedia is not usable for academic work because it contains many inaccuracies and much false information.
I don't think people who contribute to or work on Wikipedia would deny that; much information in Wikipedia is in fact inaccurate, and there are people who actually go out of their way to inject falsehoods into it.
So what? Many encyclopedias are no different. Especially those that were made with some political or religious agenda. For instance, in eight grade I remember my teacher giving my class an assignment where we had to have a look at a handful of topics in three different encyclopedias. This was a real eye-opener as at least one of the encyclopedias wanted to promote an alternate view of the world. It was a politically slanted encyclopedia filled with value judgements that, at least I, found insulting to the reader's intelligence.
And this is in the presence of an agenda. There are still what I would refer to as "honest errors" in more traditional encyclopedias and textbooks.
I think it is critical for students to understand this: that all sources of information need to be evaluated. That books, web-sites and people are fallible. In order to arrive at a probable truth you need to investigate claims and analyze sources. In this sense, Wikipedia is the perfect teaching tool. Not only does it contain more articles on more topics than any encyclopedia, but it is a living work -- a constant work in progress and a work that anyone can monitor.
If you want to teach people a sensible approach to uncovering facts, just banning Wikipedia because the information in it might be wrong, is not only silly, but academically suspect. It presupposes that there are infallible sources -- a way of thinking that has no place in academia.
Encourage kids to use Wikipedia. Encourage kids to routinely check sources. Encourage kids to seek out conflicting statements of fact. Encourage kids to think for themselves.