I am also curious about the friends option. I am wondering if you need to make your kids friends, since my students will be working on this activity together in the same room I don't think that I need them to be friends. I'm concerned that I am not able to see/moderate the messages that are sent between students, which would be necessary in a 4th grade classroom. I'd love feedback on this, since I want to begin using diigo with my students when school starts.