IB MYP Mathematics: The Four Assessment Criteria in Practice

This guide works through what genuinely top-band evidence looks like for each of IB Middle Years Programme Mathematics’s four assessment criteria, applied to real coursework tasks. The assessment revision notes list the four criteria and their scoring structure – this guide goes further, since knowing a criterion’s name is a different skill from producing work that satisfies its top achievement-level descriptors.

Where this fits in the subject

Although each criterion is scored separately on its own 1-8 scale, strong coursework tasks are usually designed to generate evidence for more than one criterion at once – an investigation task, for example, naturally produces both Criterion B evidence (the investigative process) and Criterion C evidence (how clearly that process is communicated). Revising each criterion in complete isolation from the others risks producing work that satisfies one criterion’s descriptors while accidentally neglecting another that the same task was also designed to assess.

Criterion A: Knowing and understanding

Top-band evidence selects and applies mathematics to solve problems in both familiar and unfamiliar situations across more than one of the four branches – number, algebra, geometry and trigonometry, statistics and probability. A common way students under-perform here is solving only familiar, textbook-style problems correctly – the top band specifically requires demonstrating the same mathematical knowledge transfers to a genuinely unfamiliar problem, not just a re-skinned version of a practised one. A familiar-situation task might ask a student to solve a given quadratic equation. An unfamiliar-situation task, testing the same underlying knowledge at a higher band, might instead describe a real scenario – finding the dimensions of a rectangular garden given its area and a relationship between its sides – that a student must first translate into a quadratic equation before solving it. The mathematical knowledge is identical, but recognising which knowledge applies to an unfamiliar framing is what the top band actually credits.

Criterion B: Investigating patterns

Top-band evidence works through a genuine mathematical investigation as a risk-taker, inquirer and critical thinker – meaning the investigation should include the student’s own reasoning process, noticing a pattern, forming a conjecture, testing it, refining or justifying it, not just a final correct generalisation presented without the working that led there. Given a sequence of figures made of dots forming increasingly large triangles, a top-band investigation does not just state the formula for the nth triangular number – it shows the process of counting dots for the first few figures, noticing the pattern in the differences between consecutive terms, forming a conjecture about the general rule, and then testing that conjecture against a further figure before presenting it as a justified general statement.

Criterion C: Communicating

Top-band evidence uses appropriate mathematical language and forms of representation consistently, both in writing and, where applicable, orally. This includes correct mathematical notation, clearly labelled diagrams or graphs, and a logical structure that a reader can follow without needing to infer missing steps. Two students reaching the same correct final answer to a problem involving simultaneous equations illustrate the distinction well: one shows only the final substitution and answer; the other shows each equation labelled, each algebraic step in sequence with correct notation, and a concluding sentence stating both solution values clearly. Only the second demonstrates top-band communication, since the criterion assesses the clarity and completeness of the mathematical communication itself, not merely whether the final answer is correct.

Criterion D: Applying mathematics in real-life contexts

Top-band evidence transfers theoretical knowledge into a genuinely real-world situation, draws valid conclusions from the mathematics performed, and reflects critically on those results – including their reasonableness and any limitations of the model used. A task asking a student to model a company’s costs using a linear equation should not stop once the equation is found and a prediction calculated. Top-band work goes on to reflect: is a linear model realistic for this real business over a long time period, or would costs more plausibly behave differently at very high or very low output levels? Explicitly discussing the model’s limitations, not just producing a numerical prediction, is what separates top-band Criterion D evidence from merely competent calculation.

How to approach it

Practise applying familiar mathematical techniques to genuinely unfamiliar real-world framings, not just recognising a technique once it is already presented in its standard textbook form, since Criterion A specifically rewards this transfer. For investigation tasks, document your reasoning process explicitly – the noticing, the conjecture, the testing – rather than working it out on scratch paper and presenting only the final justified rule. Treat mathematical notation, labelling and logical structure as part of the actual answer rather than optional presentation, since Criterion C is assessed independently of whether the final numerical answer is correct. For applied tasks, build the habit of asking whether your model or conclusion is realistic and where it might break down, since this critical reflection is what Criterion D specifically credits beyond correct calculation.

Common mistakes

Solving only familiar, practised problem types and assuming this demonstrates Criterion A fully, when top-band evidence specifically requires success on unfamiliar framings too. Presenting an investigation’s final rule or generalisation without the reasoning process (pattern-noticing, conjecture, testing) that led there, which is the most common reason Criterion B evidence falls short even when the final answer is correct. Treating clear notation and labelling as optional polish rather than part of the actual evidence Criterion C assesses. Stopping at a correct real-world calculation without reflecting on whether the model or conclusion is realistic, which limits Criterion D regardless of how accurate the underlying mathematics is.

Official syllabus

International Baccalaureate Organization, Middle Years Programme Subject Brief – Mathematics, from 2020, first assessment 2022 – the same source already cited by the full syllabus guide and the revision notes already on the site. Verified 2026-09-06.