How calculation marks are awarded
Mark schemes use a small set of mark types. The labels vary by board (AQA uses ticks with notes, OCR and Cambridge print the letters), but the logic is the same.
| Mark | Awarded for | What it means for you |
|---|---|---|
| M (method) | choosing the right equation and substituting correctly | Write the equation, then the numbers. This mark survives an arithmetic slip |
| A (accuracy) | the correct value, depending on the M mark | Only earned if the method is right |
| C (compensatory) | a correct final answer implies earlier marks | A bare correct answer usually scores full marks, but a wrong bare answer scores zero |
| B (independent) | a stand-alone point, such as a unit or a fact | Can be earned even if other parts are wrong |
Error carried forward
If you get part (a) wrong and then use your wrong value correctly in part (b), you lose marks only in (a). This is error carried forward (ecf), and it only helps if the examiner can see what you did.
Suppose part (b) asks for the power when the wire above is connected to 6.0 V. A student who got 3.3 Ω writes . That earns full marks in (b), because the method is right and the value follows from their (a). A student who writes only “11 W” gets nothing: the examiner cannot tell it came from ecf.
Three habits make ecf work for you:
- Label every intermediate result (“current = 0.457 A”) so it can be traced.
- Always attempt later parts. If you could not get (a), use a sensible value (or the “show that” value) and carry on.
- Keep unrounded values in the calculator. With the correct 13.13 Ω, W, so 2.7 W. Rounding the current to 0.46 A first gives W, so 2.8 W. Most schemes accept both, but a chain of early roundings can push you outside the accepted range.
Significant figures, units and standard form
- Final answers: give the same number of significant figures as the least precise data, usually 2 or 3. One extra is normally tolerated. Giving six figures from the calculator can lose a mark where the scheme penalises it.
- Estimates: give 1 or 2 s.f. and state the values you assumed (“mass of a car ≈ 1000 kg”).
- Units: a missing or wrong unit loses the unit mark where there is one. Use SI with negative indices: m s⁻², J K⁻¹ mol⁻¹.
- Prefixes and standard form: convert to SI before substituting (mm → m, µF → F, MeV → J), and write , never 1.26E-7.
Show-that questions
A show-that question gives you the answer, so the marks are for the working. The rules are strict:
- Start from a physics equation in symbols. Do not start from the given answer and work backwards.
- Substitute every value visibly, including constants from the data booklet.
- Give the result to at least one more significant figure than the value quoted. If asked to show that something is “about m”, your working must end at something like m.
- even if your own value differs slightly.
Derivations (“show that ”) work the same way: state the principle, equate the expressions, show each algebraic step and say why a term drops out (“the satellite’s mass cancels”).
Levels-of-response and extended-writing answers
AQA 6-mark questions, OCR A asterisked questions and Eduqas/WJEC extended responses are marked holistically by level. The examiner reads the whole answer, places it in a level, then picks a mark within it:
| Level | Marks | Typical profile |
|---|---|---|
| 3 | 5–6 | All strands of the question covered with correct, linked physics and a logical order |
| 2 | 3–4 | Two strands covered well, or all three partially; some gaps in reasoning |
| 1 | 1–2 | A few relevant points with little connection between them |
Edexcel 9PH0 and IAL 6-mark extended-writing questions are marked differently: up to 4 marks for indicative-content points and up to 2 marks for structure (linked, fully sustained lines of reasoning). Five correct but disconnected points score only 3, while the same points joined with “so” and “because” can score 5.
A 60-second plan
- Find the strands. Most 6-mark questions have two or three clear parts: describe and explain, or method, analysis and precautions. Write them as margin headings.
- List 2–3 physics points per strand, using key terms, quantities and equations.
- Write in linked sentences. Each sentence should state a fact and its consequence.
- Stop when every strand is covered. Extra material earns nothing and costs time.
For method descriptions, use a fixed order: apparatus (with the instruments named), independent variable and how it is changed, dependent variable and how it is measured, control variables, range and repeats, the graph to plot, and how the result comes from the gradient or intercept. Add one specific safety point if the question asks for it.
Practice routine
- One structured question a day, marked against a Courselo mark scheme. Log which mark type you lost (M, A, unit, s.f. or level).
- One 6-mark answer a week, written in 8 minutes and checked strand by strand.
- Rewrite rather than re-read: redo corrected answers from scratch two days later.