"Describe", "explain" and "discuss" look like three ways of saying "write about this." They aren't. Each one asks for a different kind of answer, and students who treat them as interchangeable tend to write long, accurate paragraphs that collect only some of the marks. The knowledge is there. The construction is off.
This guide is about construction. For each of the three words it shows a question, a weak answer, an improved answer and what changed between them, using one A Level subject throughout so the comparison is fair. It sits within our wider guide to A Level command words explained, which covers the full range of words, and it stays narrowly on how to build these three answers. For learning from what examiners say about real candidates, see how to use A Level examiner reports. For questions that give you data to work from, see how to answer data-response questions.
The examples use A Level Biology because it moves easily between data, mechanisms and issues. The same ideas apply in other subjects, but definitions and expectations vary, so check the command-word table in your own syllabus. The sample answers are illustrations of structure, not model answers for any particular paper.
Three Words, Three Shapes of Answer
| Command word | The question underneath | The shape of a good answer |
|---|---|---|
| Describe | What does it look like or involve? | A series of accurate statements, with figures or specific features |
| Explain | Why does it happen, or how? | A chain of linked reasons, from cause to effect |
| Discuss | What are the different sides or issues? | Several points or viewpoints, weighed, with a conclusion |
The rest of this guide builds each shape using the same topic: vaccination and the spread of an infectious disease. Changing only the command word shows how much the answer has to change.
Describe: Say What You See, Precisely
Suppose a table shows vaccination coverage and the number of cases of a disease in a town over three years.
| Year | Vaccination coverage (%) | Cases of the disease |
|---|---|---|
| 2015 | 40 | 900 |
| 2018 | 70 | 400 |
| 2021 | 90 | 60 |
| Weak answer | Improved answer |
|---|---|
| "The more people are vaccinated, the fewer cases there are, because vaccines stop the disease." | "As vaccination coverage increases from 40% to 90%, the number of cases falls from 900 to 60, a decrease of 840. The fall is fairly steady: about 17 fewer cases for each extra percentage point of coverage." |
What changed? The weak answer states the trend loosely and then slips into an explanation ("because vaccines stop the disease"), which the question didn't ask for. The improved answer describes only: it names the direction, quotes figures from the table and adds a measured comment on how the change behaves. Its figures are checkable, and that is what makes a description convincing.
- Quote data. Use the numbers and units in the table or graph, not just "rises" or "falls".
- Say how it changes. Steady, rapid, levelling off, a peak: choose the word that fits.
- Leave out the why. Explanations belong to a different command word and use up time.
Explain: Build a Chain of Reasons
| Weak answer | Improved answer |
|---|---|
| "Vaccination stops people getting ill, so fewer people get the disease and the number of cases goes down." | "Vaccinated people have memory cells for the pathogen, so if they are exposed they produce antibodies quickly and usually do not become infectious. With fewer infectious people, there are fewer sources of infection, so the pathogen is passed on less often. This also reduces the chance of unvaccinated people meeting an infectious person, so the whole population is better protected." |
The weak answer restates the question in different words: fewer people get ill, so there are fewer cases. It never says how or why. The improved answer moves step by step. Memory cells lead to a quick antibody response, which leads to not becoming infectious, which leads to fewer sources of infection, which leads to less transmission, which protects others. Each link answers the question "and why does that happen?"
- Look for the because. If a sentence has no reason in it, it is probably a description.
- Link each step to the next. Words such as "so", "which means" and "therefore" show the chain.
- Use the right terms. Precise vocabulary, such as memory cells and antibodies, does part of the work for you.
- Match the length to the marks. Four marks suggests several linked steps, not a single sentence.
Discuss: Cover the Sides and Weigh Them
| Weak answer | Improved answer |
|---|---|
| "Vaccination is good because it stops diseases and saves lives, so it should be compulsory. Everyone should be vaccinated to keep people safe." | "A compulsory programme would raise coverage, which protects the whole population and, through reduced transmission, people who cannot be vaccinated for medical reasons. Against this, compulsion limits individual choice, may reduce trust in health services and could cause conflict among those with sincere objections. Rare side effects also raise questions about requiring a medical procedure. Overall, the benefits to public health are strong, but because trust and consent matter, an approach that encourages high uptake may be preferable to a legal requirement." |
The weak answer takes one side and repeats it. It may be well meant, but it doesn't discuss, because it never considers another view. The improved answer sets out points on both sides, uses reasons for each and ends with a conclusion that follows from the weighing. Whether you agree with its conclusion is less important than whether it handles the material in a balanced and supported way.
- Cover more than one side. Even if you have a view, show you understand the others.
- Support each point. A reason or piece of evidence turns an opinion into an argument.
- Weigh, then conclude. Say which considerations matter more and why.
- Check the subject. In some subjects, discuss is expected to include evaluation. Your syllabus and mark schemes will show what counts.
The Three Answers Side by Side
| Aspect | Describe | Explain | Discuss |
|---|---|---|---|
| Main verb of the answer | States | Links | Weighs |
| Typical evidence | Figures, features, steps | Mechanisms, reasons | Arguments, examples, data |
| Typical opening | "As X increases, Y..." | "This happens because..." | "On one hand... on the other..." |
| Ends with | The pattern, fully stated | The final effect | A supported conclusion |
| Common failing | Slipping into reasons | Restating the question | Taking only one side |
The openings are only illustrations of the thinking involved, not phrases to memorise. The substance is what earns credit.
The Same Contrast in Physics
To see that this is not just a Biology habit, here are two short pairs from Physics. The first uses a velocity–time graph that shows a car speeding up uniformly from rest to 12 m s⁻¹ in 6 s and then moving at a constant 12 m s⁻¹ for 4 s.
| Question | Weak answer | Improved answer |
|---|---|---|
| Describe the motion of the car shown on the graph. | "The car speeds up and then goes at a steady speed." | "The car accelerates uniformly from rest to 12 m s⁻¹ in 6 s, an acceleration of 2.0 m s⁻², then travels at a constant 12 m s⁻¹ for the next 4 s." |
| Explain why a satellite in a circular orbit is accelerating even though its speed is constant. | "Because gravity is pulling on it." | "Its direction of motion is continually changing, so its velocity is changing, and a change in velocity is an acceleration. The gravitational force acts towards the centre, perpendicular to the velocity, so it changes the direction without changing the speed." |
The patterns match the Biology ones. The describe answer gains figures and a calculated value, and nothing else. The explain answer stops naming a cause and starts linking it to the effect, step by step. In both, the improvement comes from the structure of the answer, not from extra facts.
Fixing a Weak Answer in Three Questions
- 1
What did the command word ask for? Underline it, then say in your own words what shape of answer it wants.
- 2
What is my answer actually doing? Is it stating, linking or weighing, and does that match?
- 3
What is missing? Figures for a description, a link for an explanation, another side or a conclusion for a discussion.
Try this on answers you've already written. Take one that lost marks, name what it did, name what it should have done and rewrite it. A handful of rewrites teaches you more than reading a dozen model answers.
Length, Marks and Time
As a rough guide, the marks suggest how many points the examiner expects. Three marks for a description suggests about three precise statements. Four marks for an explanation suggests a chain of three or four linked steps. Six marks for a discussion suggests several developed points and a conclusion. If you've written much more than that for a few marks, you may have answered a different command word. If you've written much less, you've probably not developed it enough. Examiner reports can show how real candidates handled this, as our guide on how to use A Level examiner reports explains. When a question supplies data, the skills in how to answer data-response questions apply too.
The Same Ideas in Other Subjects
- Physics. Describe the motion shown on a graph, using values. Explain why a satellite in circular orbit accelerates, linking the force to the change in direction.
- Chemistry. Describe how the boiling points of a series of compounds change. Explain the trend in terms of intermolecular forces.
- Economics. Describe what happened to a country's unemployment over a period. Explain the likely causes with a chain of reasoning. Discuss whether a policy was effective, weighing both sides.
- Sociology or English. Discuss a view by setting out competing perspectives, supporting each, and reaching a reasoned conclusion.
How each subject marks these words differs, so read mark schemes for your own papers. You can browse real papers on our A Level past papers pages and try questions on our A Level practice pages. For a subject-specific look at Biology topics, see our A Level Biology page.
Common Mistakes With These Three Words
- Explaining a describe question. You use up time on reasons nobody asked for.
- Describing an explain question. You say what happens and never why.
- Listing for a discuss question. You give points without supporting or weighing them.
- Taking one side. You miss the breadth the word asks for.
- Ignoring the data. You write in general terms when the question points to a table or graph.
- Assuming one template fits everything. Use structure as scaffolding, then let the question and marks guide you.
Final Thoughts
Describe, explain and discuss ask for three different things: what, why and which side. If you can tell, before you write, which of those the question wants, your answers become shorter where they should be short and fuller where they should be full. The skill is learned by practice, by looking at weak answers honestly and rewriting them.
For the full range of command words, read our guide to A Level command words explained. Then pick three questions from a past paper, one for each word, and write your answers with the shapes above in mind.
Practise the subjects you choose
Work through topic questions and past papers for your A Level subjects, and get your answers marked with the reasoning behind each mark.
