What about wiki privacy in contrast Google doc?
I am completely sold on Google everything and I put my 13 year-olds on it, then reality struck. Just before Christmas, we started getting shut out of docs. Turns out that Google houses YouTubes on the same server (sometimes) as our docs, so our district firewall prevents us from seeing our docs! I'm so disgusted. I can't seem to get anyone in my district to get me up to date on what's happening and Google doesn't seem to care. I'll be looking into alternative hosts this weekend with a sad, sad heart.
Thanks for the alternates, everyone. I'm trying them out, now.
I believe Google Apps for Education gets round the age problem, at least it does in the UK - but someone would need to set it up for your school.
Would a wiki do the trick? I use Wikispaces for young students and have been really pleased with it. In fact several of our older students also use wikis. Teachers can create users and no email is required, students of any age can use it. Make sure you use the correct link to get a free wiki.
Links you might find helpful for Wikis (and Google Docs) here.
KidBlog is available to students under 13 since the entire site is managed by the teacher and you can choose settings which don't allow anything to post without your approval. You can also see if your school will set up Google Apps for Education or GAFE. This allows your IT dept to create Google user accounts through a school domain and have control over usage. This means you can use it for students under 13.