Nearly two years old, but still fresh, this post by Mark Guzdial in his Computing Education Blog, is worth reading. As an aside, it has an interesting description of how/why "ordinary" users fail when they try to edit Wikipedia. Mark's Education is already Gamified (from which I came across "Just how little students learn") sheds interesting light on the current enthusiasm for badges, and why the "badge fad" needs treating with some care.
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