Science command words tell students what kind of thinking an exam question expects. The core aim of Science mastery is not to memorise a dictionary of exam verbs. It is to recognise that state, describe, explain, compare, predict, calculate and evaluate are different scientific jobs.
For students and parents searching for Science command words, exam command words, state describe explain, compare and contrast, predict, evaluate or Science answering techniques, the most useful rule is simple: answer the verb first. A scientifically correct paragraph can still underperform if it performs the wrong task.
Command words are small words with large consequences.
The 60-Second Command Word Map
- State: give the required fact or result.
- Describe: say what is observed or what pattern appears.
- Explain: give the scientific reason or mechanism.
- Compare: identify relevant similarities or differences.
- Predict: state an expected outcome based on evidence or a model.
- Suggest: propose a scientifically reasonable answer using available information.
- Calculate: use quantitative relationships.
- Evaluate: judge quality, strength, limitations or improvements.
Wait, What? “Describe” and “Explain” Are Not the Same?
Exactly.
Suppose a graph rises as temperature increases.
Describe: the rate increases as temperature increases over the stated range.
Explain: use the relevant scientific model to show why the rate changes.
Description reports the pattern.
Explanation supplies the mechanism.
State
State questions usually need a direct answer.
Do not add a long explanation unless the question also asks for one.
Examples:
- state the unit;
- state the trend;
- state which material is the best conductor.
Precision beats length.
Describe
Describe what the evidence shows.
Useful language includes:
- increases;
- decreases;
- remains constant;
- reaches a maximum;
- levels off;
- changes more rapidly.
Use data where relevant.
Explain
Explain asks for the scientific reason.
Use:
condition → process → effect.
Or:
evidence → relationship → concept → mechanism.
Compare
Compare the same feature under aligned conditions.
Use:
A is ___, whereas B is ___.
Where possible, support the comparison with evidence.
Predict
Predict questions ask what is expected under a new condition.
A strong response includes:
- the predicted outcome;
- the evidence or model supporting it.
Suggest
Suggest usually means the answer may not be explicitly given but should be scientifically plausible.
Students should use:
- the evidence;
- relevant scientific knowledge;
- reasonable inference.
A suggestion is not random speculation.
Calculate
Calculation questions need:
- the correct formula;
- compatible units;
- clear substitution;
- final unit;
- appropriate precision.
See Science Calculations.
Evaluate
Evaluate asks for judgement.
For experiments, use:
weakness → effect → improvement.
For evidence, ask:
- how strong;
- how reliable;
- how valid;
- what limitations remain.
Identify
Identify asks the student to recognise the relevant object, structure, pattern or feature.
It usually requires less explanation than “explain”.
Do not over-answer unless needed.
Outline
Outline asks for the main points without full detail.
The response should show the sequence or structure clearly.
This command is common in more advanced Science courses.
Discuss
Discuss often requires a balanced treatment of multiple factors or interpretations.
Students may need:
- evidence for;
- evidence against;
- limitations;
- a reasoned conclusion.
Always follow the conventions of the specific syllabus.
A Worked Example: One Graph, Four Command Words
Graph: reaction rate rises with temperature to a maximum, then falls.
State: state the temperature at maximum rate.
Describe: describe how rate changes with temperature.
Explain: explain the rise and fall using the relevant model.
Predict: predict the rate at a nearby untested temperature.
The same graph demands different thinking depending on the verb.
Primary Science Command Words
Primary students should become comfortable with:
- state;
- describe;
- explain;
- compare;
- predict;
- suggest.
Teachers and parents can ask students to say what each word requires before answering.
Secondary Science Command Words
Secondary students should increasingly handle:
- calculate;
- evaluate;
- justify;
- discuss;
- deduce;
- outline.
The exact set depends on the syllabus and subject.
How to Practise Command Words
Take ten questions and do not answer them yet.
For each question, write only:
- the command word;
- the required response type;
- the evidence needed.
This trains task recognition before content recall.
Common Command-Word Mistakes
- explaining when asked to state;
- describing when asked to explain;
- giving one side when asked to compare;
- suggesting without evidence;
- evaluating without judgement;
- ignoring words such as “using the data”.
Frequently Asked Questions
What are Science command words?
They are instruction verbs that specify the kind of scientific response required in a question.
What is the difference between describe and explain?
Describe states what is observed or shown. Explain gives the scientific reason or mechanism.
What does evaluate mean in Science?
Evaluate means make a reasoned judgement about evidence, method quality, limitations or improvements.
How can I learn command words?
Practise classifying questions by command word before answering them, then compare the structure of strong responses.
Useful eduKateSG Routes
- Science Answering Techniques
- Science Open-Ended Questions
- Scientific Explanation
- Experiment Evaluation
The Core Aim
Science command words tell you what kind of answer the question is asking you to build.
State the fact. Describe the pattern. Explain the mechanism. Compare like with like. Predict from evidence. Evaluate with reasons.
That is the core aim: answer the scientific task that was actually set.
Properly taught kids shine a bright light into the future.