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IB Peer Marking: How to Mark a Classmate's Work Fairly

IB Peer Marking: How to Mark a Classmate's Work Fairly

12 min readOliver Kidd (Co-founder)5 Nov 2026

IB peer marking is a classroom activity in which you judge a classmate’s work against criteria your teacher provides, then give written feedback. It is formative, so it helps you learn and does not count towards your final grade. Done well, it sharpens your sense of what examiners reward. This guide shows how to do it step by step. It also answers a common follow-up question: when to use flashcards and when to use notes.

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TL;DR

  • Peer marking in the IB Diploma Programme is formative feedback. Official marks come from IB examiners and from teachers whose internal assessment the IB moderates.
  • Mark against the published criteria and level descriptors, never against how other students did.
  • Good feedback is specific, kind and actionable, and it talks about the work rather than the person.
  • Marking a peer’s answer is also strong revision, because it forces you to apply a mark scheme.
  • Use flashcards to test recall and notes to build understanding, and combine them in one routine.

Table of Contents

What peer marking means in the IB

Peer marking, or peer assessment, means students evaluate each other’s work. At one IB school, for example, the DP assessment policy says students may assess peers individually or in small groups using clear criteria from the teacher. They then say what was done well and what could improve.

This is not the same as official marking. The same policy describes peer assessment as formative, while IB final examinations are assessed by IB examiners. The IB’s own guidance on assessment in the Diploma Programme adds that formative assessment gives feedback to students and teachers. Teachers mark internal assessment, and the IB externally moderates it.

So your classmate’s mark on your lab write-up is a learning signal. It is not a grade that goes anywhere official. That should take pressure off both the marker and the person being marked.

What peer marking means in the IB

Mark against criteria, not against classmates

The IB describes its assessment as criterion-related. Work is judged against identified attainment levels rather than compared with other students. For a peer marker, that gives one rule: ask which level descriptor best matches the evidence on the page.

In practice:

  1. Read the criterion or mark scheme before you read the work.
  2. Read the answer once without scoring.
  3. Go through it again and tick each point where the evidence matches a descriptor.
  4. Pick the level that fits best and write one sentence of evidence for it.
  5. Check you have not scored higher or lower because you know the writer.

For a deeper look at how bands and descriptors work, our guide to IB assessment criteria walks through them.

A university writing centre recommends using a rubric that reflects the assignment requirements and weighting. It also recommends scoring each category and explaining each score, and tackling big-picture issues before grammar and clarity (University of Missouri). In a science answer, “big picture” means the content: is the reasoning correct, complete and linked to the question? Wording comes second.

A quick science example

Imagine a classmate’s answer explaining why enzyme activity falls at high temperature. Your mark scheme expects three things: the idea of denaturation, a change in active site shape, and a consequence for substrate binding. Your classmate gives the first and third but never mentions the active site. A fair peer mark credits two of three points and says so plainly: “You explained denaturation and the effect on binding. Add how the active site shape changes.” That comment is far more useful than “good, but needs more detail”.

How to give feedback that helps

Feedback works when it is specific and actionable and focuses on the work, not the person. Kapor Foundation guidance also says teachers should train and coach students, clarify criteria and moderate feedback so nobody is misled.

A medical-education study of peer review found that a few habits improved feedback quality. It used the same rubric for faculty and students and required written comments alongside scores. It also stressed specific improvement comments, descriptive and nonjudgmental language, balance and actionable suggestions (PMC study).

A simple structure many classrooms use is the Ladder of Feedback. Digital Promise describes it as moving through four steps:

  • Ask clarifying questions.
  • Name strengths.
  • Raise concerns constructively.
  • Offer suggestions for improvement.

Try this wording:

  • Instead of “This is wrong”, write “The mark scheme asks for X, and I could not find it in paragraph two.”
  • Instead of “Messy”, write “Labelling the axes would make the trend easier to follow.”
  • Instead of “Great!”, write “Your use of data in the second sentence matches the evaluation descriptor.”

What teachers should check

Peer marking works best when a teacher stays involved. Research in the International Journal of Curriculum and Instruction says the teacher’s moderating role is crucial. Without continuous oversight, peer assessment can produce grade inflation and social tension.

A short checklist for teachers:

  • Share the exact criteria before the activity, and model one marked example.
  • Spot-check a sample of peer marks against your own using the same rubric.
  • Keep the stakes low. The same research notes that weighting matters when peer evaluation counts for something, because too little weight invites free-riding and too much overburdens students.
  • Make sure written comments, not just numbers, are required.

The IB’s programme standards and practices also ask schools to put support materials, resources and processes in place for fair and valid assessment. A clear peer-marking routine fits that aim.

Why marking someone else’s work improves your own

Assessing a peer lets you reflect on and explain your understanding, and it can help you spot your own misunderstandings, according to Digital Promise. That is why peer marking is worth doing even when your partner’s work is stronger than yours. You see another route to a full-mark answer.

You can borrow the idea when revising alone. Take a past-paper answer, mark it line by line against the mark scheme, and note what each point needed. Our piece on the real role of past papers explains how to turn that marking into progress.

Why marking someone else's work improves your own

Flashcards vs notes: which one when?

Many students searching for peer marking also ask whether flashcards or notes serve them better. They do different jobs.

Flashcards Notes
Best for Testing recall of terms, definitions, equations Building understanding and seeing how ideas connect
Main action Retrieve the answer from memory Organise, summarise, explain
Use when Closer to a test, filling gaps Learning a topic for the first time
Pair with Short quizzes and past-paper questions Self-testing by covering and recalling

Flashcards test recall, and notes can be turned into self-tests too. Scientific American describes listing key terms or questions in a column, covering the notes and answering from memory.

Why does testing yourself help? A US Department of Energy report describes the testing effect as robust and says well-implemented testing can aid long-term retention. A 2014 study found classroom quizzes can lift later exam performance even when the quiz format differs from the exam.

A simple weekly routine:

  1. Write concise notes after each lesson, in your own words.
  2. Turn the key terms and “why” questions into flashcards the same week.
  3. Review cards in short sessions, then cover and recall from your notes.
  4. Finish with exam-style questions and mark them against the mark scheme, ideally with a study partner.

Our Biology guide covers flashcards and active recall and concise revision notes in more detail.

Our perspective

Peer marking is a good habit, and it gets better when the marking tools are good. A classmate can only mark fairly if the mark scheme is clear and written the way examiners think. That is why we build our materials with actual IB examiners and keep them aligned to the current exam cycle.

We designed Tiber Tutor so that resources work together. A question links to its notes, its video and its flashcards. Student-led answer review lets you mark your own response against an examiner mark scheme, which is peer marking’s best skill practised on your own schedule. Progress tracking and analytics then show which topics and command terms are costing you marks.

We believe this combination of exam-style questions, examiner-authored content and performance insight is not matched on any other IB STEM platform. At $9 per subject or $19 for everything each month, we also believe it is the best value for money available, because the content comes from people who actually mark IB papers.

Oliver

Try it with exam-style material

If you want practice that mirrors the real thing, Tiber Tutor gives you exam-style questions, examiner mark schemes, flashcards, notes, animated videos and topic tests across IB Biology, Chemistry, Physics and Maths. Every attempt feeds your progress tracking, so you can see strengths and gaps by topic.

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The Per-Subject Plan is $9 per month and the All-Access Plan is $19 per month, both after a free 7-day trial. See our pricing, or go straight to the IB Biology mock exams to practise full-paper marking. Parents can find a guide on our page for IB parents.

FAQ

Does peer marking count towards my IB grade?

No. Peer assessment is a formative activity used for feedback and learning. Your final grades come from IB examiners and from internal assessment marked by your teacher and moderated by the IB.

How do I mark a classmate’s work fairly?

Use the criteria or mark scheme your teacher gives you, not your impression of the person. Match the evidence to the level descriptors, write a reason for each score, and keep comments about the work. Ask your teacher to check a few marks if you are unsure.

What should I write in peer feedback?

Name one or two strengths, then one or two specific improvements, with a suggestion for each. Use neutral, descriptive wording such as “the mark scheme asks for X” rather than judgements about ability.

Should I use flashcards or notes for IB revision?

Use both. Notes help you understand and connect ideas when learning a topic. Flashcards help you practise recall. Cover your notes and answer questions from memory, then make cards for whatever you missed.

Sources