MYP Biology: Designing a Biology Investigation (Criterion B) FAQ

You answer them by working through four strands in order: state a testable research question and hypothesis with scientific reasoning, explain how you'll control variables, describe a logical step-by-step method with enough detail to repeat it, and address safety and environmental factors. Miss a strand and you cap your mark regardless of how good the rest is.

Criterion B has four strands, each marked out of 2 on an 0-8 scale: explaining the research question, formulating a hypothesis with scientific reasoning, explaining variable control and data collection, and designing a safe, logical, complete method. Top marks (7-8) need all four done thoroughly, not just attempted.

A testable hypothesis predicts a specific, measurable outcome and gives scientific reasoning for why you expect it — not just "X will increase." For example: "As light intensity increases from 10 to 50 lux, the rate of photosynthesis in Elodea will increase, because more light energy drives more photolysis reactions."

You need three types: the independent variable (what you deliberately change), the dependent variable (what you measure as a result), and controlled variables (everything else kept constant so it doesn't affect your result). List each controlled variable with how you'll actually control it — that's the part examiners check for.

Most MYP schools expect at least three repeats per condition so you can calculate a mean and spot anomalies — the MYP guide itself doesn't fix a number, but three is the standard taught across DP too, so examiners expect to see it justified in your method. Fewer than three weakens your reliability strand in Criterion C.

A full-marks method is numbered, uses precise quantities and equipment (not "some water" but "20ml distilled water"), states how the dependent variable is measured, includes repeats, and reads as a stand-alone set of instructions someone else could follow exactly and get comparable results.

You name the actual hazard (not "be careful"), state the specific precaution, and — where relevant — note environmental or ethical impact, like safe disposal of chemicals or humane treatment of living organisms. Generic statements like "wear goggles" without linking to a real risk rarely score the mark.

The three biggest mark-losers I see every year: hypotheses with no scientific reasoning attached, variable lists with no explanation of how each is controlled, and methods too vague to repeat. Fix those three and most students move from a 4-5 into the 7-8 band without changing anything else.

A strong research question names both variables explicitly and is phrased so it can only be answered by collecting data: "What is the effect of substrate concentration on the rate of catalase-driven oxygen production?" is testable; "Does concentration matter?" is not specific enough to plan a method from.

Criterion B (Inquiring and Designing) is about planning — your question, hypothesis, variables and method, written before you collect data. Criterion C (Processing and Evaluating) is about what you did with the results afterwards — tables, graphs, conclusions and evaluating your method's limitations. They're assessed separately, on different pieces of work.

Yes — Criterion B assesses your design, not whether the experiment was physically run, so a well-planned hypothetical investigation can score full marks. Many schools set Criterion B as a stand-alone design task precisely for this reason, separate from the data you process under Criterion C.

Criterion B is marked out of 8, using the same 1-8 MYP achievement-level descriptors as the other three science criteria. A 7-8 needs all four strands done thoroughly with scientific reasoning; a 5-6 is a solid, mostly complete design with a few gaps. Your child's final subject grade blends all four criteria (A-D), not B alone.

The fastest improvement usually comes from practising past design tasks against the actual strand descriptors rather than just reading more biology content — most students already know the science; they lose marks on structure and specificity. Topical worksheets and past-paper-style questions with mark schemes on RevisionPrep let your child self-check against exactly what examiners reward.