I am using Wikiversity in an effort to develop open source cirricula, and for that reason, am keenly aware of Wikipedia's limitations as a teaching tool. Wikipedia does not and should not attempt to be a textbook. There is no proper way to make a long article about such a basic concept as Deviation. But, for the textbook writer, a clear understanding of basic definitions is essential. When writing teaching materials, terminology must be clearly defined, both in an early chapter, as well as in a glossary.
I need this page, and the question is which wiki should host it. Wiktionary is not intended to be a glossary and is entirely unsuitable. In theory, Wikiversity is structured to contain glossaries and someday that might happen. But at the moment Wikiversity is so underdeveloped that a glossary is out of the question. For one thing, students are apt to edit it, and they are pretty much free to write whatever they wish.
For me it is essential that these "glossary" items be kept in Wikipedia where more editorial control is maintained. I will link to this article from Wikiversity