O-Level Physics Paper 3 Command Word Decoder

> **TL;DR**\
> SEAB’s glossary defines exactly what verbs such as “describe”, “determine”, “suggest”, and “evaluate” demand in Paper 3 ([SEAB 2026 Physics syllabus](https://www.seab.gov.sg/files/O%20Lvl%20Syllabus%20Sch%20Cddts/2026/6091_y26_sy.pdf)).\
> Align every response segment with the verb: Planning answers need measurable methods when you see “define” or “outline”, MMO scripts must “measure” with quoted precision, PDO prompts triggered by “plot” or “state” expect unit-labelled tables, and ACE responses to “comment”, “predict”, or “suggest” require evidence-backed evaluation.\
> Use the templates below to practice writing verb-aware responses before the practical window.

---

## 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](https://www.seab.gov.sg/files/O%20Lvl%20Syllabus%20Sch%20Cddts/2026/6091_y26_sy.pdf)). | 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 \~5 %.”            |
| **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 \\( R = V / I \\). 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.”                                     |
| **Evaluate**   | Discuss limitations and improvements.       | “Evaluate 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 \\( \Delta T \\).”                       |
| **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 \\( \sqrt\{2} \\) according to \\( v = \sqrt\{T / \mu} \\).” |

For full ACE marks, always combine the verb with uncertainty comment and explicit improvement.

---

## 6 | Practice worksheet: verb swap drill

```text
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

```text
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

1. [SEAB, GCE O-Level Physics (6091) Syllabus 2026 — Glossary of Terms](https://www.seab.gov.sg/files/O%20Lvl%20Syllabus%20Sch%20Cddts/2026/6091_y26_sy.pdf)