This information comes from Andrea Robertson and David Young at Dunedin College of Education:

What's a wiki?
A wiki is a web site that lets any visitor become a participant: you can create or edit the actual site contents without any special technical knowledge or tools. All you need is a computer with an Internet connection. A wiki is continuously “under revision.” It is a living collaboration whose purpose is the sharing of the creative process and product by many. One famous example is Wiki-pedia, an online encyclopedia with no “authors” but millions of contributors and editors. The word "wiki" comes from Hawaiian language, meaning "quick" or "fast." Copied from http://www.teachersfirst.com/content/wiki/

This site is for teachers and allows you to create an advertisment free wiki http://www.wikispaces.com/site/for/teachers

Andrea's step by step instructions for
external image pdf.png
external image pdf.png
Creating and Using a Wiki with Wikispaces.pdf

Here are some examples of school wikis - have a look and write down some ideas...
http://strathtaieri.wikispaces.com/
http://bradford.wikispaces.com/
http://arborheights.wikispaces.com/
http://haultain-math.wikispaces.com/

Tips from wikispaces for teachers
http://www.wikispaces.com/help+Teachers

Wikispaces help
http://www.wikispaces.com/help+index

OR Wiki's could be used like an intranet page for maths groups, reading groups etc:
http://e-maths.wikispaces.com/classpage