Students should not be “grading” each other. They should be doing formative assessment and giving formative feedback to their peers. As a person emailed me, students do not learn to be formative unless they are taught.
In elementary, language arts learn give valuable feedback telling several good things and then to give constructive feedback wording like “I wonder what would happen if ….” Middle school schools can identify if parts of a science lab reports exist. They can identify if certain essay writing has a thesis statement and topic sentences. They can share their strategies withe their peers. By late middle school, students should be capable of giving detailed feedback based on checklists, rubrics, exemplars, etc. Again, each comment helps the peer t to improve.
We talk about life long learning and one aspect of that is wanting to improve. Peers can offer valuable feedback. Often peers can word things in ways that are very understandable to the other students as opposed to the jargon of some teachers. Peers can provide feedback more frequently than the teacher.
How to help your students to grow in giving formative feedback.