MYP Chemistry Assessment Criteria A to D Explained

According to the IB's MYP: Sciences guide (part of the MYP: From Principles into Practice framework), every science subject — Chemistry, Biology, Physics — uses this identical four-criterion structure, though the task-specific descriptors differ by subject.

The three strands examiners actually mark:

1. Explain scientific knowledge.
2. Apply knowledge and understanding to solve problems in familiar and unfamiliar situations.
3. Analyse and evaluate information to make scientifically supported judgments.

Quick tip: if a test question describes a reaction you've never studied but gives you the data to reason through, that's a Criterion A unfamiliar-context question — not a trick.

Four strands make up Criterion B:

• Explain the problem or question to be tested
• Formulate a testable hypothesis using scientific reasoning
• Explain how to manipulate variables and collect sufficient, relevant data
• Design a method that is safe, ethical and repeatable

Common mistake: stating a hypothesis as just a prediction ("the rate will increase") without the chemistry reasoning behind why — that caps you around level 3-4.

Worked example: if a titre reads 25.00 cm³ with an uncertainty of ±0.05 cm³ on each of two readings, the total uncertainty is 0.10 cm³, giving a percentage uncertainty of (0.10 ÷ 25.00) × 100 = 0.4%. Quoting that figure — and explaining whether it's small enough to trust the conclusion — is what separates a level 5-6 evaluation from a level 7-8 one.

Common mistake: writing "repeat the experiment more times" as your improvement. Examiners want a change to equipment, technique or control variables, with a reason attached.

The four strands:

1. Explain how science is applied to a specific problem or issue.
2. Discuss and evaluate the implications of that application.
3. Apply scientific language accurately and consistently.
4. Document sources using a recognised referencing system.

Common mistake: answering Criterion D questions with Criterion A-style content (more explanation of the reaction) instead of the actual implications — who benefits, what's the environmental cost, what's the ethical trade-off.

Worked example: a student scores A=6, B=7, C=6, D=7. Total = 26, which typically falls in the 24-27 band, converting to a grade 6. Two more marks (28) would push them into grade 7 territory — which is why chasing the weakest criterion, not the strongest, usually moves the final grade fastest.

In practice: an MYP 4 Criterion C task might ask you to plot a graph and identify a trend. An MYP 5 task on the same criterion might expect a calculated percentage error, a discussion of anomalies, and a specific method redesign — same criterion, noticeably higher bar.

Quick tip: if you know you underperformed on a Criterion B task, ask your teacher when the next Criterion B opportunity is rather than assuming it's over for the year — it usually isn't.

Before you submit a lab report, check:

1. Have you included an uncertainty or error calculation, not just raw numbers?
2. Does your evaluation reference your actual data, not a generic phrase?
3. Have you proposed an improvement you could genuinely carry out with school equipment?

The uncertainty calculation from the earlier titration example (0.4%) is exactly the kind of specific figure that lifts an evaluation from level 5-6 to 7-8.

If your Criterion D paragraph could be pasted into a Criterion A answer without anyone noticing, it's the wrong content. Ask yourself: does this sentence discuss who's affected, what trade-off exists, or what the environmental/ethical cost is? If not, it belongs somewhere else.

Worked step-by-step for a titration investigation:

1. Research question: "How does concentration of HCl affect the volume of NaOH needed for neutralisation?"
2. Hypothesis: "As HCl concentration increases, less NaOH will be needed, because a smaller volume will contain the same number of moles of acid."
3. Variables: independent = HCl concentration; dependent = titre volume; controlled = temperature, indicator volume, NaOH concentration.
4. Method: state exact volumes (e.g. 25.0 cm³ HCl), equipment (burette, ±0.05 cm³), and number of repeats (at least 3 for a mean).

According to the IB, first assessments for the current DP Chemistry guide were in 2025, and its Internal Assessment is a single scientific investigation marked against different criteria to MYP's four. See the comparison table below for a fuller side-by-side.

If your child is deciding between DP Chemistry HL, SL or a different science, ask their MYP teacher for a criterion-by-criterion breakdown rather than just the overall 1-7. A student weak specifically in Criterion A (content recall and application) faces a different risk at DP level than one weak in Criterion D.

Quick tip: ask your child to identify, before starting a lab write-up, which criterion each section of the report is scoring against. Students who can name "this paragraph is Criterion C" while writing it consistently score higher than those who write one long undifferentiated report.