One of the first things I was told as a trainee teacher back in the UK was that "the person doing the work is the person doing the learning." It's a catchy phrase, and it's the foundation of the peer-marking craze that has swept through schools from Somerset to Shanghai. The idea is simple: instead of the teacher marking every piece of work, the students mark each others'.
The Broad Debate
The "progressive" side of the debate sees peer marking as a way to empower students. They argue that by marking a classmate’s work, a student learns to identify success criteria. The "old school" side, however, sees it as a lazy shortcut—a way for teachers to avoid taking a heavy bag of books home.
What the Thinkers Say
The educational establishment—the "polite bubble" of people who write the policy documents—is almost universally in favour of peer marking. They speak beautifully about "metacognition" and "student agency." They treat it as an unalloyed good.
But Sitting in a classroom in Shanghai on a Wednesday afternoon, the realpolitik is much messier. Rory Stewart or Alastair Campbell might argue that an informed peer-review system is the backbone of any healthy institution, but they haven't seen a Year 9 boy try to mark his best friend's essay. Most thinkers assume students are being honest and objective. In reality, students are biased, confused, and often just want to get to the end of the lesson.
My View
My view is that peer marking is a brilliant teaching tool, but it’s a terrible marking tool. If you use it to generate a grade or to save yourself time, you’re failing your students. But if you use it to teach them how to think like a marker, it’s an act of truth. As Naval Ravikant might say, it’s about providing students with the "leverage" of understanding the system they are working in. The goal shouldn’t be a score; it should be the moment of clarity when a student finally sees why a piece of work succeeded or failed.
Why it Often Fails
The "Blind leading the Blind"
If a student hasn't mastered the concept themselves, they can't possibly identify if their peer has mastered it. Without an extremely specific, almost "industrial" rubric (reminiscent of the precision I saw in M&A contracts), peer marking just turns into "I think this looks good." It’s the blind leading the blind.
Social Realpolitik
Students are social creatures. When you ask a 14-year-old to mark their peer's work, you're asking them to navigate a minefield. They either mark too generously to stay popular, or too harshly if there's a rivalry. The "objective marker" doesn't exist in a classroom of teenagers. Kindness in this context is being honest about these social dynamics, not ignoring them.
What Happens Next?
If you want to use peer marking effectively, you have to be much more rigorous about it:
- Never use it for final grades: Peer marking is a "formative" tool. Use it during the draft stage.
- The "Check the Checker" Rule: I always mark a random sample of the peer-marked work. If the student marker was inaccurate, they have to redo it. It keeps everyone honest.
- Focus on Specificity: Don't ask students to mark "the whole essay." Ask them to mark just the topic sentences. Specificity is the only way to get around a lack of expertise.
For teachers: Peer marking isn't a shortcut. Done properly, it’s actually more work. But the payoff isn't a grade in a spreadsheet—it's a student who finally understands the "why" behind the "what."