IB MYP Mathematics: The Four Assessment Criteria in Practice -- Revision Notes

The assessment revision notes list the four criteria and their scoring structure. These notes go further, working through what genuinely top-band evidence looks like for each criterion with a worked example, since knowing a criterion’s name is a different skill from producing work that satisfies its top achievement-level descriptors.

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.

Worked example: 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 (e.g. 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.

Worked example: 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.

Worked example: Two students reach the same correct final answer to a problem involving simultaneous equations. 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.

Worked example: 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.

Why treating the four criteria as fully independent is a mistake

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.

Self-test

1. What distinguishes top-band Criterion A evidence from correctly solving only familiar problems?
2. What must a top-band Criterion B investigation include beyond a correct final generalisation?
3. Name two features of top-band Criterion C communication.
4. What must top-band Criterion D evidence include beyond a correct real-world calculation?
5. Why can a single coursework task often generate evidence for more than one criterion at once?

Answers: 1. It requires applying the same mathematical knowledge successfully to a genuinely unfamiliar situation, not just a familiar or practised problem type. 2. The reasoning process itself – noticing a pattern, forming a conjecture, and testing or justifying it – not just the final correct rule. 3. Any two of: correct mathematical notation, clearly labelled diagrams or graphs, a logical structure a reader can follow without inferring missing steps. 4. A critical reflection on the result’s reasonableness and the model’s limitations, not just a correct final numerical answer. 5. Because a well-designed task (such as an investigation) naturally produces evidence relevant to more than one criterion simultaneously, e.g. both the investigative process (Criterion B) and how clearly it is communicated (Criterion C).

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, which first reproduced the four criteria’s names and focus areas from it.