REVISION GUIDE · EXAM TECHNIQUE

Command words: what the question is really asking

State, describe, explain, evaluate… learn what each command word means in Cambridge IGCSE and A Level Computer Science, and how to turn knowledge into marks.

Most lost marks in Computer Science exams are not about missing knowledge. They happen because the answer does not do what the question asked. The first word of every question, the command word, tells you exactly what the examiner wants. Learn these words and you will know how much to write, whether you need a reason, and how to pick up every available mark.

This guide covers the command words used in Cambridge IGCSE Computer Science (0478) and AS and A Level Computer Science (9618), explained in plain language with Computer Science examples. The official definitions are listed in each Cambridge syllabus.

The four types of question

Almost every command word falls into one of four groups. Spot the group first and you already know the shape of your answer.

RECALLState, Identify, Give, DefineA short fact or term. One mark each. No explanation needed.

DESCRIBEDescribe, Outline, SummariseSay what something is or does, or list the steps in order. One mark per relevant point.

REASONExplain, JustifySay why or how. Every point needs a reason linked with “because”, “so that” or “which means”.

JUDGECompare, Evaluate, Discuss, AssessLook at both sides, then weigh them up. Often worth 4 to 8 marks.

Command words and what they mean

Choose your course to see the words used in your exams.

Word	What to do	Example question
Calculate	Work out a value from the figures given. Show your working.	Calculate the file size of the image in kibibytes.
Compare	Give similarities or differences, mentioning both things in each point.	Compare serial and parallel data transmission.
Define	Give the exact meaning of a term.	Define the term embedded system.
Demonstrate	Show how something works, often with a worked example.	Demonstrate how a bubble sort reorders this list.
Describe	Say what something is or does, or set out the steps in order.	Describe how a firewall protects a network.
Evaluate	Weigh up strengths and weaknesses, then make a judgement.	Evaluate the use of cloud storage for a school.
Explain	Give reasons or say how and why, linking each point to its effect.	Explain why a computer needs both RAM and ROM.
Give	Write a short answer from memory or from information provided.	Give two examples of an input device.
Identify	Name, pick out or recognise something.	Identify the logic gate shown in the diagram.
Outline	Set out the main points briefly, without detail.	Outline the stages of the fetch-decode-execute cycle.
Show (that)	Give step-by-step working that reaches the stated answer.	Show that 10110110 in binary is B6 in hexadecimal.
State	Write a clear, short fact. No reason needed.	State one function of an operating system.
Suggest	Apply what you know to a new situation where several answers could be right.	Suggest a suitable validation check for the age field.

Word	What to do	Example question
Analyse	Break something down in detail and show how the parts relate.	Analyse the algorithm to find why it outputs the wrong total.
Assess	Make a reasoned judgement.	Assess the suitability of a star topology for the office.
Calculate	Work out a value from the figures given. Show your working.	Calculate the number of usable hosts in this subnet.
Comment	Give a reasoned opinion.	Comment on the choice of a waterfall model for this project.
Compare	Give similarities or differences, mentioning both things in each point.	Compare RISC and CISC processors.
Complete	Fill in a table, diagram or algorithm.	Complete the trace table for the algorithm.
Consider	Read the given information carefully and respond to it.	Consider the E-R diagram and identify the foreign key.
Contrast	Give differences only.	Contrast a compiler with an interpreter.
Define	Give the exact meaning of a term.	Define the term referential integrity.
Demonstrate	Show how something works, often with a worked example.	Demonstrate how a stack is used to evaluate this RPN expression.
Describe	Say what something is or does, or set out the steps in order.	Describe how CSMA/CD handles collisions.
Develop	Take an idea or design further.	Develop the pseudocode to also count invalid entries.
Discuss	Write in depth about an issue, covering different points of view in a structured way.	Discuss the ethical issues of using AI to mark exams.
Draw	Draw lines to match items, or draw the diagram asked for.	Draw a line to match each protocol to its layer.
Evaluate	Weigh up strengths and weaknesses, then make a judgement.	Evaluate the use of a virtual machine for testing software.
Examine	Look closely at something in detail.	Examine the code and locate the logic error.
Explain	Give reasons or say how and why, linking each point to its effect.	Explain why floating-point numbers are normalised.
Give	Write a short answer from memory or from information provided.	Give one benefit of using a DLL.
Identify	Name, pick out or recognise something.	Identify the addressing mode used in LDM #5.
Justify	Back up a choice or claim with reasons or evidence.	Justify your choice of data structure for the queue.
Outline	Set out the main points briefly, without detail.	Outline the stages of compilation.
Predict	Say what is likely to happen, based on the information given.	Predict the output when the input is 7.
Sketch	Make a simple drawing showing the key features.	Sketch the structure chart for the program.
State	Write a clear, short fact. No reason needed.	State the purpose of the program counter.
Suggest	Apply what you know to a new situation where several answers could be right.	Suggest how the company could reduce disk thrashing.
Summarise	Give the main points only, without detail.	Summarise the advantages of packet switching.
Write	Produce an answer in the form asked for, such as pseudocode or program code.	Write pseudocode for a function that returns the largest value.

How to use the marks

One mark usually means one point. A 3-mark Describe question needs three separate, relevant points.
Explain marks often come in pairs. A 4-mark Explain question usually means two points, each with its reason: the point earns one mark and the “because…” earns the second.
Compare needs both sides in every point. Use “whereas”: “Fibre-optic cable uses light, whereas copper cable uses electrical signals.” Writing about only one of the two items scores nothing.
Don’t repeat the question. Rewording the question earns no marks. Add something new in every sentence.
Use the technical term. Write “volatile”, not “it forgets things”; “protocol”, not “rules thing”.
Answer in context. If the question is about a school, a shop or a robot, mention it. Generic answers often miss the mark.

One topic, three command words

See how the same topic needs a different answer depending on the command word.

1. State one function of a firewall. [1]

Full marksIt monitors incoming and outgoing network traffic. That’s all you need.

Wasted timeWriting a paragraph about hackers. There is still only 1 mark available.

2. Describe how a firewall protects a network. [3]

Weak (1 mark)It stops hackers and keeps the network safe.

Strong (3 marks)It checks all traffic entering and leaving the network. It compares each packet with a set of rules. It blocks traffic that does not meet the rules, such as packets from blocked IP addresses.

3. Explain why a school should use a firewall. [4]

Weak (1 mark)Because it is secure and protects the computers.

Strong (4 marks)It blocks unauthorised access from the internet, so hackers cannot steal student records. It can filter outgoing traffic, which means students cannot reach unsuitable websites.

Planning a 6-mark answer

Longer Evaluate and Discuss questions are marked on the quality of your argument as well as your points. Use this plan:

Underline the command word and the context (for example: evaluate, cloud storage, a school).
Make 2 or 3 points for, each with a reason linked to the context.
Make 2 or 3 points against, each with a reason linked to the context.
Finish with a justified conclusion. Say which side is stronger for this situation, and why.

Example opening: “Cloud storage would let teachers access resources from home, because files are stored online rather than on one computer. However, it depends on a reliable internet connection, so lessons could be disrupted if the school’s connection fails…”

In IGCSE Paper 2, the final 15-mark scenario question needs a full algorithm rather than an essay. See the IGCSE revision checklist for tips on timing it.

Try it: what is the question asking?

Read each question and choose what kind of answer it needs.

Frequently asked questions

What is a command word in Cambridge Computer Science?

A command word is the instruction word at the start of a question, such as state, describe or explain. It tells you what kind of answer the examiner wants and how much detail to give.

What is the difference between describe and explain?

Describe means say what something is or what happens. Explain means say why or how, so each point needs a reason, usually linked with because, so that or which means.

How many points should I write for a 4-mark question?

Usually four separate points for state or describe questions. For explain questions, two points each with a linked reason is often enough, because each reason earns its own mark.

Want help turning knowledge into marks?

Book a free 30-minute online lesson. We will practise exam technique on the questions you find hardest. Book a free demo →