At a glance
- Where Cambridge lists them
- Command words table near the end of each 0610, 0620 and 0625 syllabus
- Where Pearson lists them
- Appendix 5, command word taxonomy, in each International GCSE science specification
- Rule of thumb
- one creditworthy point per mark
- Most confused pair
- describe (what) versus explain (why or how)
The command words that matter most
Definitions in quotation marks are from the Cambridge 2026 to 2028 science syllabuses and the Pearson Edexcel International GCSE taxonomy.
| Command word | Cambridge meaning | Edexcel meaning | What to write |
|---|---|---|---|
| State / Give | "express in clear terms" / "produce an answer from a given source or recall/memory" | Give, state and name are "really synonyms" requiring recall | A short fact, no explanation needed |
| Define | "give precise meaning" | Edexcel uses "state what is meant by" | The textbook definition, word for word |
| Describe | "state the points of a topic / give characteristics and main features" | "give an account of something"; no justification needed | What happens or what the data shows, with numbers |
| Explain | "set out purposes or reasons / make the relationships between things clear / say why and/or how" | Must contain "some element of reasoning/justification" | Point plus because, so or which means |
| Suggest | Apply knowledge where there is "a range of valid responses" | "propose a solution to a problem in a novel context" | A sensible idea linked to science you know |
| Calculate | "work out from given facts, figures or information" | "obtain a numerical answer, showing relevant working" | Equation, substitution, answer, unit |
| Determine | "establish an answer using the information available" | Must have a quantitative element | Use the graph or data; show the reading or calculation |
| Evaluate | "judge or calculate the quality, importance, amount, or value of something" | Weigh strengths and weaknesses and reach a supported judgement | For and against, then a conclusion |
| Compare | "identify/comment on similarities and/or differences" | (used in questions; not in the taxonomy) | Matched statements: X is ... whereas Y is ... |
| Sketch | "simple freehand drawing showing the key features" | For a graph: line and labelled axes, axes not scaled | Correct shape and labelled axes, no plotted points |
The exact list differs by subject: the Chemistry table also includes analyse, consider, contrast, deduce, demonstrate, discuss, examine, justify and show; Physics includes comment, deduce and justify. Check the table in your own syllabus.
Worked example 1: describe versus explain on the same graph
Question (Biology): a graph shows enzyme activity rising from 10 °C to a peak at 40 °C, then falling to zero at 60 °C.
Describe (2 marks): "Activity increases as temperature rises from 10 °C to 40 °C. Above 40 °C activity decreases and reaches zero at 60 °C." No reasons; quoting the values of the turning point and end point earns the marks.
Explain (3 marks): "As temperature increases, molecules have more kinetic energy, so there are more frequent effective collisions between enzyme and substrate. Above 40 °C the active site changes shape, so the substrate no longer fits and the enzyme is denatured." Each sentence contains a reason linked with so or because.
Worked example 2: calculate and show that
Calculate (Physics, 3 marks): a car travels 150 m in 12 s. Calculate its average speed. Write the equation: speed = distance ÷ time. Substitute: speed = 150 ÷ 12. Answer with unit: 12.5 m/s. If the arithmetic slips, the equation and substitution usually still earn method marks; a bare wrong number earns nothing.
Show that (Edexcel): the question gives you the answer, for example "show that the speed is about 12 m/s". The marks are for the working, so write every step and give your answer to more significant figures than the question (12.5 m/s, not just 12). Then use the given value in later parts if your own answer differs.
Worked example 3: suggest and evaluate
Suggest (Chemistry): "Suggest why the reaction in the second flask was slower." There is no single answer; credit goes to any reason consistent with chemistry and the information, such as the acid being more dilute or the marble chips being larger, so there was a smaller surface area and fewer collisions per second. Do not write "I don't know, it was not in the syllabus": suggest questions are deliberately set in unfamiliar contexts.
Evaluate (all three sciences): weigh evidence both ways, then judge. "The data supports the claim because the rate doubles between 20 °C and 30 °C in all three repeats. However, only three temperatures were tested and one repeat at 30 °C is anomalous, so the conclusion is only tentative." A judgement with no evidence, or evidence with no judgement, rarely reaches full marks.
Common mistakes
- Describing when the question says explain, so the answer has no because.
- Explaining when the question says describe or state, wasting time that a later question needs.
- Writing one long point for a 4-mark question. Count the marks and make that many separate points.
- Giving a calculated answer with no unit or the wrong number of significant figures when the question specifies them.
- Drawing a sketch graph with plotted points and a scale but unlabelled axes.
- Answering compare questions with two separate lists instead of matched comparisons.
- Repeating the question back as the answer, which earns nothing.
How examiners use the mark scheme
Mark schemes list acceptable points, alternative wording that is allowed (often shown after a slash or as "allow") and wording that is rejected ("reject" or "ignore"). Vague words such as "it", "affects" or "changes" without a direction are often ignored. Key technical terms (diffusion, denatured, electrons, refraction) frequently have to appear, and a correct idea with a wrong technical word can lose the mark. That is why the most effective revision is answering past questions and then reading the mark scheme line by line, not reading notes.
In longer Edexcel questions, and in Cambridge structured questions worth several marks, a clear order helps the examiner find your points. Short sentences, one idea each, with the key term in each, are easier to credit than one long paragraph.
How one-to-one lessons help
Command words are a skill, not a topic, so they improve fastest with feedback on real answers. A tutor sets past questions with mixed command words, asks the student to underline the command word and count the marks before writing, then marks the answer against the official mark scheme and shows which phrase earned or missed each mark. Over a few weeks this habit transfers across biology, chemistry and physics at once.
Self-check before every answer
- Have I underlined the command word?
- How many marks, and do I have that many separate points?
- If it says explain, does every point contain a reason?
- If it says describe and there is data, have I quoted numbers with units?
- If it says calculate, have I written the equation, the substitution, the answer and the unit?
- If it says suggest, have I linked my idea to a scientific reason?
- Have I used the key technical term the mark scheme is likely to need?
Common questions
Are command words the same in Cambridge and Edexcel?
Most are shared, but the definitions are written differently and each board has some of its own. Pearson uses "show that", "comment on" and "state what is meant by"; Cambridge uses define, outline and, in Chemistry, words such as contrast and demonstrate. Use your own board's list.
Are the command words the same in Biology, Chemistry and Physics?
Not exactly. In the Cambridge 2026 to 2028 syllabuses the Chemistry table is the longest, and Physics includes comment and justify. The core words (state, describe, explain, suggest, calculate, evaluate) appear in all three.
Do I lose marks for writing too much?
Not usually for extra correct material, but a contradiction can cancel a correct point, and time spent on a 1-mark question is time lost elsewhere.
How much do LiveTutor science lessons cost?
$15 a lesson for every subject and level, booked as a weekly plan of 1 to 5 lessons billed monthly. Lessons are 60 minutes, one to one and online, and the first lesson is a free trial.
What is the difference between suggest and predict?
Predict asks what is likely to happen based on information (Cambridge: "suggest what may happen based on available information"). Suggest asks for a reasoned proposal where more than one answer could be valid.
Sources
Dates and figures on this page come from these official and published sources. Always confirm deadlines on the official page before acting on them.