Approve new pages/posts for all blogs

Hey guys,
I am running an edublog for my sixth grade students. I want to monitor and approve (also grade) all new pages/posts that my students add. How may this be accomplished through the admin panel?

My ultimate goal would be the ability to grade and add notes to each post before it's approved. Obviously, that'd require some more custom work. I'd be happy right now if I could just moderate every post/page addition. I'm currently running the content monitor and user activity plugins but they don't quite serve my purpose.

Thanks,
Colin