Those of you that have tried out Diigo with middle/high school students, how do you address concerns about the accessibility it presents to unknown users? I noticed students can easily wander into other groups, including some in the "Romance & Relationships" category that sound very inappropriate. I would love to use Diigo with students, but I worry that encouraging use of this tool could be construed as condoning some of these inappropriate/risky areas and present a liability issue. Your thoughts?