MYP Maths Assessment Criteria A to D Explained

According to the IB, this four-criterion structure comes from the MYP: Mathematics guide (for use from 2020, first assessed 2022) and hasn't changed for the current syllabus cycle.

Each criterion is assessed at least twice a year in most MYP 4-5 programmes, so no single test decides your grade.

The three strands examiners look for:

1. Selecting appropriate mathematics for the problem.
2. Applying it accurately, with correct method.
3. Getting the right solution in a range of contexts, including ones you haven't drilled before.

Quick tip: students lose marks here not through wrong maths, but through picking the wrong tool — e.g. using the sine rule when the cosine rule fits the given sides.

Worked example — counting diagonals in a polygon:

1. Draw polygons with n = 4, 5, 6 sides; count diagonals: 2, 5, 9.
2. Spot the pattern in first differences (3, 4…) and propose a rule: $\frac{n(n-3)}{2}$.
3. Verify with n = 7: rule gives 14, matches the actual count.
4. Justify using combinatorics: total line segments $\left(\genfrac{}{}{0ex}{}{n}{2}\right)$ minus the n sides.

Step 4 is what pushes a level 5-6 investigation into level 7-8.

What examiners actually check:

• Consistent, correct mathematical notation throughout.
• At least two forms of representation (e.g. table plus graph) when the task allows it.
• A conclusion that connects back to the original question.

Common mistake: writing correct working with no linking sentences. Examiners can't award full marks for a line of reasoning they have to reconstruct themselves.

Strands examiners assess: identifying relevant real-life elements, selecting a strategy, applying it correctly, then justifying accuracy and whether the final answer is realistic.

Example: modelling the cost of a phone contract over 24 months. Getting the algebra right earns Criterion A marks — but noting that a fractional 'number of texts' doesn't make sense, and rounding sensibly, is what earns Criterion D marks.

Roughly, higher totals map like this (boundaries vary slightly by school and cohort):

Treat this as a guide, not a fixed rule — your school's boundaries are the ones that count.

Note that a level 8 doesn't mean flawless — the level 7-8 descriptor band usually requires 'consistently' meeting the standard across a task, not perfection on every single line. That's why one small slip rarely drops you a full band.

In my experience marking MYP work, the biggest gap between grade 5 students and grade 7 students isn't Criterion A accuracy — it's Criterion B justification and Criterion D sense-checking. Students who are technically excellent at Criterion A often plateau at grade 5-6 because they never push their investigations or applications into the top band.

3 things to check before submitting an investigation:

1. Have you tested the rule on a case you didn't use to find it?
2. Have you tried to prove the rule algebraically, even partially?
3. Have you stated any limitations — does the rule break down for small n, negative numbers, or edge cases?

Skipping step 3 is the single most common reason level 6 investigations don't reach level 7-8.

Quick tip: if a question gives you a real-world scenario (a phone bill, a road trip, a recipe) and asks you to model it, expect it to be assessing Criterion D even if the underlying maths — linear equations, percentages — is Criterion A content you already know.

A reliable structure:

1. State the task and any variables you'll use.
2. Work through 3-4 simple cases and record results in a table.
3. Spot the pattern and propose a general rule.
4. Test the rule on a new, unused case.
5. Justify the rule algebraically or explain why it must hold.
6. Note any limitations of the rule.

Skipping straight from step 3 to step 6 is the most common structural fault I see in MYP 4-5 investigations.

Most schools also use a maths department recommendation alongside these signals, so treat criterion levels as one input, not the whole decision.

When choosing resources, check they clearly label which criterion each task targets — a worksheet that just says "algebra practice" won't tell your child whether they're building Criterion A accuracy or Criterion C communication skills, and those need different feedback.