O-Level Physics Paper 3 Command Word Decoder
TL;DR
SEAB’s glossary defines what command words such as “define”, “describe”, “explain”, “measure”, “determine”, “suggest”, and “predict/deduce” demand in answers (SEAB 2026 Physics syllabus glossary).
Align every response segment with the verb: Planning answers need measurable methods when you see “define” or “describe”, MMO scripts must “measure” with quoted precision, PDO prompts triggered by “plot” or “state” expect unit-labelled tables, and ACE responses should use evidence-backed evaluation when you’re asked to “discuss” or “suggest” improvements.
Use the templates below to practice writing verb-aware responses before the practical window.
Keep Your Physics Practical Stack On Track
Use our O-Level Physics Experiments hub to find companion drills for every Paper 3 skill before you attempt these walkthroughs.
1 | Command-word overview at a glance
| Command word | Glossary meaning | Paper 3 focus | Template starter |
|---|---|---|---|
| Define | Give a formal statement or defining equation (SEAB 2026 Physics syllabus glossary). | Planning intro, e.g. “Define the physical quantity you are measuring.” | “The specific heat capacity (c) is the energy required per kilogram per kelvin, i.e. (Q = mc\Delta T).” |
| Describe | State main points, include observations where relevant (same source). | MMO narrative or step-by-step method. | “Describe how you align the lens: level the bench, centre the lens on the optical axis, adjust screen until image sharpens.” |
| Explain | Provide definition plus significance/context (same source). | ACE commentary linking data to theory. | “Explain why the gradient differs from theory: heating increased resistance, raising the (V) - (I) slope by about five percent.” |
| Determine | Obtain by calculation using measured/known values (same source). | PDO computation. | “Determine (g) from your graph: gradient of (s) vs (0.5 t^2) equals (g).” |
| Measure | Obtain directly using an instrument (same source). | MMO precision emphasis. | “Measure the mass with the 0.01 g balance; record as (85.32 \pm 0.01 , \text{g}).” |
| Predict / Deduce | Apply logical connection, possibly from earlier answers (same source). | ACE extrapolation or planning justification. | “Predict the effect of doubling coil turns: induced emf doubles because (E \propto N).” |
| Suggest | Provide plausible response; may have multiple answers (same source). | ACE improvements. | “Suggest an improvement: use a mirror-scale to reduce parallax when reading the rule.” |
| Sketch | Qualitative graph or diagram, showing key features (same source). | PDO quick plots, planning diagrams. | “Sketch the cooling curve showing initial steep drop then exponential tail; label temperature/time axes.” |
2 | Planning prompts decoded
| Typical wording | What examiners want | Response checklist |
|---|---|---|
| “Define the variables you will investigate.” | Formal statement with units. | Independent/dependent variables; control list with SI units. |
| “Describe how you would determine the resistance…” | Stepwise method tied to instruments. | Sequential steps, instrument resolution, repeats, safety. |
| “Suggest how to reduce risk/error…” | Plausible improvement linked to hazard. | Identify hazard → mitigation (gloves, insulation, etc.) → state impact on data. |
Template paragraph:
“Define the aim as determining the resistance (R) of the wire using . Measure current with an ammeter (0.01 A resolution) and voltage with a voltmeter (0.1 V). Describe connecting the wire in series with a rheostat, taking readings at 0.5 V intervals, and allowing the wire to cool between runs. Suggest using a low-voltage supply to limit heating and reduce resistance drift.”
3 | MMO verbs and precision cues
- Measure: quote instrument, resolution, and reading.\
- Record: transcribe value with unit and significant figures.\
- Observe: note qualitative trends (colour change, alignment, oscillation damping).\
- Repeat: collect multiple readings; mention averaging.
Example: “Measure the oscillation period using a stopwatch (0.1 s); record ten oscillations to average reaction time. Observe whether amplitude decreases, noting if damping affects timing. Repeat twice more to compute a mean (T).”
4 | PDO command words turned into action
| Verb | Action | Micro habit |
|---|---|---|
| Tabulate | Create a table with headings, units, repeat columns. | Use solidus notation (Time, t / s). |
| Plot | Draw graph with labelled axes, best-fit line. | Scale uses ≥50 % grid; points as small crosses. |
| State / Write down | Provide numeric result clearly with units. | Quote to allowed significant figures. |
| Sketch | Produce qualitative graph or apparatus diagram. | Highlight intercepts/slopes/axes but no detailed plotting. |
If the question says “Determine and state,” attach unit and sig.-fig discipline; if it says “Plot and draw,” ensure balanced best-fit line and gradient triangle.
5 | ACE command words and response templates
| Verb | Expectation | Template sentence |
|---|---|---|
| Comment on | Provide interpretation linked to data. | “Comment on the trend: voltage increases linearly with current, confirming Ohm’s law.” |
| Discuss | Give a critical account of the points involved. | “Discuss the method: heating increased resistance, so allow cooling or use smaller currents to maintain linearity.” |
| Explain | Link result to theory/mechanism. | “Explain why the cooling curve flattens: temperature approaches ambient, reducing .” |
| Suggest | Propose plausible improvement or next step. | “Suggest using a digital datalogger to reduce timing reaction error.” |
| Predict | Extrapolate based on relationship. | “Predict that doubling string tension increases wave speed by according to .” |
For full ACE marks, always combine the verb with uncertainty comment and explicit improvement.
6 | Practice worksheet: verb swap drill
Command Word Drill
------------------
1. Original prompt: "Describe how you would measure the specific heat capacity."
Response:
- Introduce aim with equation.
- List apparatus + resolutions.
- Sequential steps + repeats + safety.
2. Rewrite the prompt with each of the following verbs:
a. Explain why...
b. Suggest how...
c. Evaluate the method.
3. For each new verb, write a two-sentence answer matching the required depth.
Repeat weekly-swap verbs from past practicals to build flexibility.
7 | Command-word checklist for mock marking
Paper 3 Command Word Checklist
------------------------------
Station / Date:
[ ] Planning answer defines aim + variables (define/describe)
[ ] Method steps align with "describe/measure" verbs
[ ] Table/graph tasks meet "tabulate/plot" requirements
[ ] PDO results respond to "state/determine" with units + sig figs
[ ] ACE section covers "comment/explain/evaluate" with data reference
[ ] Improvements match "suggest/predict" expectations
Use this during peer review-circle verbs that were missed and rewrite the response immediately.
Sources
Practical course completion-record note
For practical, lab, and experiment courses, Eclat Institute maintains centre-held attendance records and may also issue an internal attendance or completion document based on participation and internal assessment.
- For SEAB private-candidate declarations, the key evidence is the centre's attendance or completion record, not a government-issued certificate.
- This is an internal centre-issued certificate, not an MOE/SEAB qualification or accreditation.
- Recognition (if any) is determined by the receiving school, institution, or employer.
- For SEAB private candidates taking science practical papers, SEAB states you should either have taken the subject before or attend a practical course and complete it before the practical paper date.
View our sample completion document (Current sample layout (design may be refined over time))
