There are quite a few tools that let you make free wikis.

Wiki info:

https://wikiwhileyouwork.wikispaces.com/workshop

https://www.teachersfirst.com/content/wiki/wikiideas1.cfm

Wiki Websites:

Wikispaces: https://www.wikispaces.com/site/for/teachers  

Example wiki made with wikispaces 

*Wikispaces is free to use; if you sign up for an educator account you get lots of customizable allowances, and the teacher can set up usernames/passwords so the students don't need email addresses.

PB Works: https://plans.pbworks.com/academic/?utm_campaign=nav-tracking&utm_source=Top%20navigation

***Frisco ISD also has a wiki. If you would like a wiki through the Frisco ISD Apple Server, email your class rosters and the name you'd like to call your wiki to your technology facilitator.