I have to give a presentation to a group of middle school students, and the activity I have planned is to have them start their own blog. Ideally, I'd like to have them set up a Tumblr account because it is easy and straightforward.

However, the pr0n. I'd rather not be the one to introduce anyone to that ecosphere if I can help it.

Thoughts? Is there an alternative to Tumblr that has more stringent content requirements, but is as simple to use?