MYP Chemistry Command Terms Explained

Command terms are the specific verbs the IB uses in every MYP Chemistry task — words like 'state', 'explain' or 'evaluate' — that tell you exactly what kind of response is expected. According to the IB's MYP: Sciences guide, each term maps to a precise cognitive demand, and misreading it is the fastest way to lose marks on a factually correct answer.

'State' wants a brief fact with no reasoning attached — a name, value or equation. 'Describe' asks for a detailed, accurate account of what happens, still without reasons. 'Explain' goes further and demands the cause or mechanism behind it — the why, not just the what. Confusing these three costs real marks in Criterion A tasks.

'Evaluate' asks you to weigh up the strengths and limitations of a method, result or claim and reach a supported judgement — it isn't just listing pros and cons. In Criterion C (processing and evaluating), examiners want comment on reliability, validity or the impact of errors, followed by a clear conclusion.

The IB's MYP: Sciences guide lists around 30 command terms shared across all MYP sciences, from 'annotate' and 'calculate' through to 'synthesize'. Your teacher has access to the full glossary in the subject guide, and keeping a shortlist of the terms tied to Criterion A-D pinned above your desk pays off during revision.

Chemically correct isn't the same as command-term correct. If a question says 'explain' and you only 'describe' — stating what happens without saying why — the examiner can't award marks for reasoning that simply isn't on the page, however accurate your facts are. I see this constantly with strong students on rate-of-reaction questions.

Each of the four MYP Sciences criteria favours certain command terms. Criterion A (knowing and understanding) leans on 'state', 'describe' and 'explain'. Criterion B (inquiring and designing) uses 'formulate' and 'design'. Criterion C (processing and evaluating) relies on 'interpret' and 'evaluate'. Criterion D (reflecting on impacts) uses 'discuss' and 'justify'.

The biggest one I mark down every year is treating 'explain' as 'describe' — students recount an observation beautifully but never say why it happens. A close second is answering 'justify' questions with an opinion and no evidence attached, which scores zero even when the opinion itself is scientifically sound.

An 'explain' answer needs a claim, a reason and a link back to chemistry theory — not just a description of what you observed. Structure it as: state what happens, say why it happens using a concept like bonding, energy or particle behaviour, then connect that reason directly to the question asked.

Both terms want balance, not an information dump. For 'discuss', present at least two sides of an issue — say, nuclear power versus fossil fuels — with evidence for each before a reasoned conclusion. For 'evaluate', focus specifically on the strengths and weaknesses of a method or claim, then judge its overall reliability.

Take last term's tasksheet and rewrite three questions, swapping the command term — turn a 'describe' into an 'explain', a 'state' into an 'evaluate' — then answer both versions and compare what actually changes. This trains you to spot the verb before you touch the content, which is exactly what examiners test.

Many words overlap — 'state', 'describe', 'explain', 'evaluate' — but the cognitive demand rises sharply at Diploma level. DP Chemistry, with first exams for the current guide in 2025, adds terms like 'deduce' and 'derive' that rarely appear before MYP 5. The core skill of matching depth to verb is exactly the same one you're building now.

Yes — if your school enters you for the optional IB MYP eAssessment in Year 5, the on-screen chemistry tasks use the same command term glossary as classroom assessments, just under timed conditions. Practising command terms under time pressure, not only in untimed homework, is what actually prepares you for that format.

Command terms teach a transferable skill — reading an instruction precisely before answering it — which matters whether your child continues to DP Chemistry, moves to A-Levels, or leaves the IB system after MYP. It's the same instruction-following habit that examiners and university markers reward everywhere, so it's worth building properly now.