I loved this blog post from Two Writing Teachers on "Guess Your Feedback" Their suggested activity is to give strips of paper with teacher written feedback/comments to a group of students. The team's task is to figure out which feedback comment matches which of their pieces and how they could fix what needed to be revised.
Giving freedom while also providing structure during peer editing is always a challenge. My students thrive on the opportunity to look at each other's work and to put in their two cents on how it should look. As wonderful as this collaboration can be, it can also spiral quickly into social time and irrelevant revisions.
I've had success with my students using SnagIt to record their peer editing meetings. This holds them accountable when they know that their discussion is being recorded and it also gives them something to reference back to. I love the idea of pairing this with Two Writing Teachers idea of giving teacher-created feedback on strips of paper for them to match to their piece. I predict meaningful conversation if this activity was extended to also include, "find this same/similar area for improvement in your partner's piece" after they've made corrections in their own. Providing students with this activity to guide their peer editing not only gives them structure to their meeting, but also models different areas of improvement to hunt for in their writing. I can't wait to try it!