Susan Sedro in Minnesota, U.S., has some thoughts as she helps a colleague create wikis for his classes.

1. They need to be readable by families and other schools.
2. They need to be protected to some degree from spam, but still allow outsiders to leave comments.
   
3. They need to track who makes what changes, so we can track malicious editing back to the person who did it.

Moodle fails #1, PBWiki fails #3. Only Wikispaces can hack all three, but

Wikispaces meets all three criteria, but at a price. Each child receives a separate invite. Accepting the invitation makes them a member of Wikispaces and of our wiki. Since each child is a separate member, the wiki can track which user makes which changes.

But a Wikispaces person comments:

At Wikispaces, when teachers need accounts for students who don’t have email addresses we create the accounts for them in batches. The teacher just sends us a list of usernames and passwords which we create and which they can dole out as appropriate. Email addresses aren’t neccessarily needed.