Last I heard of Wikipedia and schools, teachers weren't accepting Wikipedia articles as sources for research, citing inaccuracies and vandalism. Rather than barring students from what I consider a wonderful resource, why not encourage them to participate in its growth?
Have students create an account so their contributions can be tracked. (They should be able to demonstrate ownership, to prevent dishonest students from simply claiming someone else's username.) Show them how wikis in general work, and what standards Wikipedia in particular expects of its editors. From there students can help expand stubs, verify sources, or even create their own articles.
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