What is a command word?
A command word is the instruction at the start of an exam question. It tells students what kind of answer is expected — not just what topic to write about.
In GCSE Physics, the command word determines:
- Whether to list facts or explain causes
- Whether to use precise scientific vocabulary or everyday description
- Whether to provide evidence for both sides of an argument
- Whether to apply knowledge to a new, unfamiliar situation
The most common mark-loss pattern in GCSE Physics isn't a lack of knowledge. It's answering the wrong type of question — knowing the Physics but not recognising what the command word is asking for.
AQA Evidence — 2025
"Use of vague language in explaining physics concepts was common across both papers." In one Higher-tier example highlighted by AQA, 79% of students scored zero where imprecise scientific language was the issue — not a lack of subject knowledge.
The five command words every Physics student needs
AQA GCSE Physics uses a consistent set of command words across both papers. Each requires a different type of response. Here's what each one means — and what it doesn't mean.
State the key features, steps or observations. No explanation of why is needed — but precision still matters. Vague descriptions score fewer marks.
"Describe how the current changes as resistance increases in a circuit at constant voltage."
Give a reason using scientific principles. Cause-and-effect relationships must be made explicit. This is where most students lose marks — by describing instead of explaining.
"Explain why the current decreases when resistance increases at constant potential difference."
Use a mathematical process to find a numerical answer. The equation, substitution, and units must all be shown. A correct final answer without working risks losing method marks.
"Calculate the resistance of a component with a voltage of 12V and a current of 3A."
Consider the strengths and limitations of something, then reach a justified conclusion. Both sides of the argument must be addressed — a one-sided response cannot reach the highest marks.
"Evaluate the use of nuclear power as an energy source."
Apply existing scientific knowledge to an unfamiliar situation. There may be more than one acceptable answer. The question is testing whether students can transfer their understanding — not whether they've memorised a specific fact.
"Suggest one reason why the reading on the ammeter might be lower than expected."
Describe vs Explain — the most common command word mistake
The distinction between describe and explain is responsible for more lost marks in GCSE Physics than almost any other single issue. Students who understand both concepts frequently lose marks by confusing which one is required.
| Command word | What it requires | What students often write instead |
|---|---|---|
| Describe | State what happens — precisely and specifically | Vague general statements ("it gets bigger", "it changes") |
| Explain | State what happens AND why, using scientific reasoning | A description without any cause-and-effect reasoning |
| Evaluate | Evidence for, evidence against, justified conclusion | A one-sided argument with no conclusion |
| Calculate | Equation shown, values substituted, units included | Only the final number, no working shown |
| Suggest | A reasoned answer applied to new context | A memorised fact that doesn't fit the new situation |
What parents can do
After a mock exam or practice paper, ask these questions instead of "how did it go?"
- Which command word was at the start of the question you found hardest?
- Did you answer what the command word asked, or did you answer the topic?
- For any explain question — did you include a cause-and-effect link?
- For any calculate question — did you show the equation and units?
- For any evaluate question — did you include evidence on both sides?
Frequently asked questions
Do command words appear on every GCSE Physics question?
Yes. Every question in AQA GCSE Physics uses a command word to indicate what type of response is expected. Identifying the command word before writing any answer is one of the most reliable exam technique habits a student can develop.
What happens if a student describes instead of explains?
The answer will be marked against the wrong level of response. A description on an explain question cannot reach the higher mark bands, regardless of how much relevant content it contains. The examiner is rewarding the type of thinking the command word requires — not just subject knowledge.
Are command words the same across all exam boards?
The core command words — describe, explain, calculate, evaluate, suggest — are consistent across AQA, Edexcel, OCR and WJEC. The exact definition may vary slightly between boards. Physics Decoded is built specifically around AQA GCSE Physics.
Can a student improve their command word recognition quickly?
Yes — it's one of the more learnable exam skills. The challenge isn't memorising the definitions. It's building the habit of reading the command word first, every time, before deciding what to write. That habit develops through deliberate practice rather than passive revision.