You know the content, you write a decent paragraph, and you still lose marks, because the question said "explain" and you only "described". Command words are the most avoidable mark-loser in Cambridge IGCSE, and learning what each one asks for takes about twenty minutes. This guide covers the IGCSE command words that appear across Biology (0610), Chemistry (0620), Physics (0625) and Computer Science (0478), with examples you can copy as a pattern.
What are IGCSE command words?
A command word is the verb at the start of a question that tells you what kind of answer earns the marks. "State", "describe", "explain" and "suggest" can all sit on the same topic, yet each needs a different answer. Cambridge publishes a definition for each one in the command words section of every syllabus, so the examiners mark against a shared meaning (Cambridge Assessment International Education, current syllabus documents for each subject; always check the wording in your own syllabus).
The marks give you a second clue. A one-mark "state" wants one short fact. A three-mark "explain" wants roughly three linked points. If your answer is far longer or shorter than the marks suggest, re-read the command word.
The IGCSE command words table
| Command word | What it asks for | Typical length |
|---|---|---|
| State | A clear, short fact. No reasons. | A word or one line |
| Give / Identify | Pick out or name something from information or knowledge | A word or phrase |
| Define | The precise meaning of a term | One exact sentence |
| Describe | What something looks like, how it changes, or what happens: features and main points | One point per mark |
| Outline | The main points only, without detail | Brief, one point per mark |
| Explain | Why or how: give the reason and link it to the cause | Point plus reason, per mark |
| Compare | Similarities and/or differences, both sides stated | Pairs of points |
| Suggest | Apply what you know to an unfamiliar situation; several answers may be valid | Short, reasoned ideas |
| Calculate | Work out a number from the data, showing your method | Working plus unit |
| Determine | Establish an answer from given information | Working or reading from data |
| Predict | Say what will happen, based on given information | Short statement |
| Justify | Support a decision with evidence | Claim plus evidence |
| Sketch | A simple, labelled drawing or graph shape | Quick diagram |
The wording above is a plain-English summary. Your syllabus's own definitions are the final authority, so print the command words page for each subject and keep it with your notes.
Describe vs explain: the pair that costs the most marks
Most lost marks come from mixing up these two.
- Describe = what. Say what you can see, measure or observe.
- Explain = why. Say what causes it, using a "because" or "so".
Worked example (Biology, 0610, diffusion and transport).
Describe how the rate of water loss from a leaf changes on a hot, windy day.
A good answer reports the pattern: the rate increases, and it is faster than on a cool, still day.
Explain why the rate of water loss from a leaf increases on a hot, windy day.
Now you need the mechanism:
- 1Higher temperature gives water molecules more kinetic energy, so evaporation from the mesophyll cell surfaces is faster.
- 2Wind removes the water vapour near the stomata, so the concentration gradient between the inside of the leaf and the air is steeper.
- 3A steeper gradient means faster diffusion of water vapour out through the stomata.
Notice that each explain point carries a reason. "It is windy so it dries out" earns less than "wind removes the water vapour, which keeps the concentration gradient steep".
Tip: For any "explain" question, test each sentence with the word "because". If you can't add one honestly, you have described something and left the reason out.
"Suggest": the command word that feels unfair
"Suggest" appears when the exam puts you in a situation you haven't seen. There is rarely one fixed answer; the examiner wants to see you apply a syllabus idea sensibly.
Worked example (Chemistry, 0620, rates of reaction).
A student heats a solution to make a reaction faster. Suggest one reason why using a higher temperature may be risky for the experiment.
You have never met this exact experiment, but you know that the products or the solution might be flammable, hot liquid can splash, and some reactions give off a gas that builds pressure. Any sensible, relevant idea can earn the mark.
How to approach it:
- 1Identify which syllabus topic the unfamiliar context is built from.
- 2Pull out the one idea from that topic that fits.
- 3Write it as a short, specific statement, linked to the situation in the question.
Avoid vague answers such as "it might go wrong". Name what goes wrong and why.
"Compare": always mention both sides
A common slip is writing about only one item. "Compare mitosis and meiosis" needs both named in each point.
- Weak: "Meiosis makes gametes."
- Strong: "Mitosis produces two genetically identical cells, whereas meiosis produces four genetically different cells."
Use link words like whereas, but, both and similarly. A table in your revision notes trains this habit, because every row forces a point about each side.
"Calculate", "determine" and "predict": show your thinking
Calculate (Physics 0625 example): A car travels 150 m in 12 s. Calculate its average speed.
- 1Write the equation: speed = distance ÷ time.
- 2Substitute: 150 ÷ 12.
- 3Give the answer with a unit: 12.5 m/s.
Method marks are often available even if the final number is wrong, so always show the equation and substitution. For the same reason, don't skip the unit. If you meet a moles problem, the same habit works step by step; our guide to IGCSE Chemistry moles calculations shows how.
Determine often means pull an answer out of a graph, table or data you've been given, so quote the values you used. Predict wants a clear outcome based on a pattern in the information, so say what will happen, and give a number where the pattern allows.
A five-step habit for every question
Use this routine in the exam, and practise it until it takes five seconds.
- 1Circle the command word.
- 2Check the marks. Roughly one clear point per mark.
- 3Underline the key terms (the topic, the conditions, the units).
- 4Answer in the right shape: fact, feature, reason, comparison or calculation.
- 5Re-read the command word before moving on, and ask whether you did what it said.
How to practise command words
Reading the table once won't stick. The research on retrieval practice is clear that recalling information from memory beats re-reading it (Roediger & Karpicke, 2006, Psychological Science), so make yourself produce answers.
- Rewrite one answer three ways. Take a topic you know, such as osmosis, and write a "state", a "describe" and an "explain" answer for it. Seeing how each differs makes the rules concrete.
- Mark your own work. After a timed question, compare your answer with the mark scheme and tag each lost mark as "knowledge", "command word" or "detail". You will probably find command-word errors are easy wins. Our guide to using topical past papers shows how to mark honestly and turn mistakes into marks.
- Teach it. Try explaining the difference between "describe" and "explain" out loud, with an example, as if to a younger student. Explaining material to someone else tends to produce better understanding than studying it again (Fiorella & Mayer, 2013, Contemporary Educational Psychology). We cover why this works in why teaching a topic is the fastest way to learn it.
- Fit it into your timetable. Put ten minutes of command-word drills inside your weekly routine. Our IGCSE study plan guide shows how to schedule practice around your exam dates.
Tip: Keep a "mark-loss log" in the back of your notebook. After each practice question, write one line on why you dropped a mark. After two weeks the patterns will show you what to fix first.
Where TeachVerse fits
TeachVerse is a study app where you learn a topic by explaining it to your own AI pupil, which only knows what you taught it and then answers exam-style questions. That forces you to practise "explain" rather than just recognise it. You can then generate a topical paper with a mark scheme to test the command words under exam conditions. The questions are original and written in the style of Cambridge IGCSE papers; TeachVerse isn't affiliated with or endorsed by Cambridge. You can try it free or see the pricing.
Quick recap
- Command words tell you what kind of answer earns marks. Content is only half the job.
- "Describe" is what, "explain" is why, "suggest" is apply what you know, and "compare" needs both sides.
- Check the marks, then match your answer length and shape to them.
- Practise by writing and marking answers, not by re-reading the table.
Pick one topic you revised this week, write a "describe" and an "explain" answer to it tonight, and check them against your notes. That ten-minute exercise is worth more than another hour of passive reading.