A student can solve an equation correctly and still need support explaining their reasoning. Another may spot a pattern quickly but struggle to justify why it works. IB MYP Mathematics assessment helps teachers recognise these different strengths and identify what students should develop next.

The four assessment criteria are A: Knowing and understanding, B: Investigating patterns, C: Communicating, and D: Applying mathematics in real-life contexts. They are equally weighted, with a maximum achievement level of 8 for each criterion. Each assesses a different aspect of mathematical learning. IB Mathematics subject brief.

For teachers, the practical challenge is designing tasks that make those aspects visible. The examples below offer starting points for lessons, assessment planning and feedback.

Photo: Artturi Jalli on Unsplash. Mathematical equations on a chalkboard.

MYP Mathematics assessment criteria at a glance

Four ways students demonstrate mathematical learning
Criterion	Focus	Student-friendly question
A	Knowing and understanding	Can I choose and use appropriate mathematics?
B	Investigating patterns	Can I discover, test and explain a mathematical rule?
C	Communicating	Can someone follow my mathematical thinking?
D	Applying mathematics in real-life contexts	Can I use mathematics to make a sensible decision?

These questions are classroom shorthand. Use the applicable IB descriptors when making assessment judgments.

Criterion A: Knowing and understanding

Criterion A assesses students’ ability to select and apply mathematics to solve problems in familiar and unfamiliar situations. IB Mathematics subject brief.

A useful assessment gives students opportunities to make mathematical choices, alongside demonstrating accurate procedures.

A rectangle has a perimeter of 42 cm. Its length is 3 cm greater than twice its width. Find its dimensions.

A student might define the width as w, making the length 2w + 3. They can then form and solve an equation:

2w + 2(2w + 3) = 42
6w + 6 = 42
w = 6

The rectangle is therefore 6 cm wide and 15 cm long. Substitution confirms that 2(6) + 2(15) = 42.

This response makes the student’s selection and application of algebra visible. A bare answer gives the teacher less evidence of how the student approached the problem.

For classroom planning, include a range of demands appropriate to the year group. A routine equation, a geometry problem requiring an equation, and an unfamiliar problem requiring students to select an approach can reveal different aspects of understanding.

Useful feedback: “Your equation represents the perimeter correctly. Check how you expanded the brackets before solving.”

Criterion B: Investigating patterns

Criterion B focuses on mathematical investigation. IB Mathematics subject brief.

A productive investigation allows students to generate results, notice relationships, propose a general rule and examine why it works.

Square tiles form a single straight row, sharing complete edges. Investigate the relationship between the number of tiles and the perimeter.

Results for rows of square tiles
Number of tiles, n	Perimeter in unit lengths, P
1	4
2	6
3	8
4	10

Students may notice that each additional tile increases the perimeter by 2 and propose P = 2n + 2.

They can test the rule with a new case. For 10 tiles, it predicts a perimeter of 22 unit lengths, which they can check independently with a diagram.

They can then explain the structure: the row has n exposed edges along the top, n along the bottom and one at each end. Therefore, P = n + n + 2 = 2n + 2.

This example helps distinguish verification from justification. Checking another case supports the rule; explaining the exposed edges establishes why it works for any positive whole number of tiles.

For younger students, the investigation could begin with physical tiles. For older students, this simple linear relationship could serve as practice before a more demanding investigation. Its suitability for summative assessment depends on the year-level descriptors and the task’s complexity.

Useful feedback: “Your rule matches your results. Explain how the arrangement of tiles accounts for each part of the formula.”

Criterion C: Communicating

Criterion C concerns how students communicate mathematical ideas through language and representations. IB Mathematics subject brief.

Teachers can make this concrete by asking whether a reader can understand the variables, follow the reasoning and connect the representations.

Return to the tile investigation. The statement “it goes up by two” leaves several questions unanswered. What increases? What does each variable represent? Which arrangements does the rule describe?

A clearer response would be:

Let n represent the number of square tiles in a straight row, and let P represent the perimeter in unit lengths. Each additional tile increases the perimeter by 2, so the relationship is P = 2n + 2, where n is a positive whole number.

A labelled diagram and table could support this explanation. If students use a graph, they should choose a representation that reflects the discrete number of tiles.

To develop communication during lessons, ask students to:

Define variables before using them.
Label diagrams, tables and graph axes.
Use mathematical notation consistently.
Explain how a representation supports a conclusion.
Organise working so the reasoning is easy to follow.

Communication becomes easier to assess when students have a reason to explain their thinking. A short investigation or comparison task can provide that opportunity.

Useful feedback: “Your table and formula describe the same relationship. Define the variables so the reader can connect them.”

Criterion D: Applying mathematics in real-life contexts

Criterion D assesses how students transfer mathematics to real-world situations, reach conclusions and reflect on their results. IB Mathematics subject brief.

A classroom task can encourage this by requiring a decision, with assumptions and practical constraints that students must consider.

A school needs transport for 146 students and 12 adults. A 48-seat coach costs $420, and a 30-seat minibus costs $290. Recommend the cheapest combination that provides enough seats. Assume everyone requires one seat and there are no additional charges.

Students first establish that transport is needed for 146 + 12 = 158 people. They can compare feasible options:

Vehicle combinations providing at least 158 seats
Coaches	Minibuses	Total seats	Total cost
4	0	192	$1,680
3	1	174	$1,550
2	3	186	$1,710
1	4	168	$1,580
0	6	180	$1,740

Under the stated assumptions, three coaches and one minibus provide the cheapest option.

The table uses the minimum number of minibuses needed for each potentially competitive coach count. Adding more vehicles would increase the cost, and five or more coaches already cost more than the recommendation. Students therefore have a basis for explaining why their comparison is sufficient.

They should also interpret the result: the recommended combination has 16 spare seats. Before making a booking, the school would need to confirm vehicle availability, accessibility requirements and whether the quoted prices include all charges.

For accuracy, students could explain that vehicles must be counted in whole numbers and capacity must meet or exceed demand. Rounding down a vehicle calculation could leave people without seats.

Useful feedback: “Your recommendation provides enough seats. Explain how you know you have considered every potentially cheaper combination.”

How should teachers use the achievement levels?

The criterion levels describe achievement against published descriptors. Teachers use a best-fit judgment, supported by evidence in the student’s work. The mathematics guide provides descriptor sets for MYP Years 1, 3 and 5, so expectations should be checked against the applicable criteria. IB Mathematics guide, assessment overview.

Avoid attaching a guaranteed level to a single feature such as “includes a formula” or “checks an answer.” The examples in this article illustrate possible evidence; they are not scored exemplars or complete assessment tasks.

Before setting a summative task, identify which strands it allows students to demonstrate. Then write task-specific clarifications that explain what those expectations look like in that particular problem.

Make the criteria part of everyday teaching

Students can practise the thinking behind the criteria in short lesson activities: choosing between two solution methods, testing a conjecture, improving an unclear explanation or checking whether an answer makes sense in context.

A useful exit ticket is: “What did you calculate, how did you establish it, and what does your result mean?”

The responses can help teachers decide whether the next lesson needs more work on mathematical understanding, investigation, communication or application—and give students a clear next step.

For support with planning across the programme, explore our IB MYP Mathematics Curriculum Map. To find teaching materials for your year group, browse our paid IB MYP Mathematics curriculum kits:

IB MYP Mathematics Assessment: Criteria A, B, C and D Explained with Examples