Why calculation marks disappear
A student can fully understand the Physics behind a calculation question, choose the right equation, and still lose marks. How? By not showing the process clearly enough for the examiner to award method marks.
AQA Physics papers are designed so that the process of calculation earns marks separately from the final answer. A student who shows correct working but makes an arithmetic error can still earn method marks. A student who writes only the final answer — even a correct one — risks losing marks if no working is shown.
This is one of the most consistent findings in AQA's examiner reports: multi-step calculation questions are a significant mark-loss area, and most of those lost marks are caused by missing working, incorrect units, or skipped steps — not mathematical inability.
AQA Evidence — 2025
AQA's 2025 examiner feedback identified multi-step calculations as a significant mark-loss area across both tiers and both papers. Students across both tiers found multi-step calculations challenging, particularly when rearranging equations, converting units, and using calculators — AQA 2025 Examiner Report.
The E-S-R-A method — four stages, every time
Physics Decoded teaches a four-stage method for every calculation question. Each stage has its own mark potential. Skipping any stage risks losing marks even when the final answer is correct.
EQUATION
Write the equation you're going to use. Every calculation starts here. No equation shown = no method marks available for this stage.
SUBSTITUTE
Put the numbers into the equation with their units. Show this step explicitly — don't do it in your head.
REARRANGE
If the equation needs rearranging, show every step. Don't rearrange mentally and jump to the answer.
ANSWER + UNITS
State the answer with the correct unit. A number without a unit is an incomplete answer and risks losing the final mark.
The key principle: a wrong final answer with correct visible method may still earn method marks — where the mark scheme awards them. A correct final answer with no working shown may score zero. Always show the process.
Unit conversion — check before substituting
One of the most consistent calculation mark-loss patterns identified by AQA is incorrect units. A correct method with the wrong units scores zero on the answer mark. Convert units before substituting into any equation.
| Convert | Multiply / Divide by | Used in |
|---|---|---|
| nm → m | × 10⁻⁹ (or ÷ 1,000,000,000) | Wave calculations |
| cm → m | ÷ 100 | Distance and length |
| g → kg | ÷ 1000 | Energy, force, momentum |
| kJ → J | × 1000 | Energy calculations |
| hours → s | × 3600 | Speed, velocity, power |
| minutes → s | × 60 | Speed, power calculations |
How the Five Performance Patterns close the gap
Calculation questions don't exist in isolation. A student who has closed all five Performance Gaps approaches calculation questions with a completely different set of habits from one who hasn't — and the marks reflect it.
Units are the language of calculation. "30" is not an answer. "30 Ω" is. Precise scientific notation — including units at every stage — is what the mark scheme rewards.
The E-S-R-A method is a structure, not just a checklist. Just as six-mark questions need PEEL, calculation questions need E-S-R-A. Structure is what makes the process visible to the examiner.
The core pattern: equation first, substitution second, rearrangement third, answer with units last. Every step shown. Every stage an opportunity for marks — even if the final answer is wrong.
Required practical questions often include calculation components — particularly percentage uncertainty. The same E-S-R-A discipline applies: show the formula, substitute the values, state the answer with units.
Calculation questions appear across both papers and carry significant mark weightings. Under AQA's published requirements, approximately 30% of Physics marks involve mathematical skills — making calculation one of the highest-priority areas for revision. Students who prioritise calculation technique as a skill — not just content knowledge — consistently outperform those who don't. The Physics Performance Gap is widest in calculation questions for students who know the Physics but haven't developed consistent process habits.
This is the Physics Performance Gap in action. A student who understands Ohm's Law but doesn't show their working, doesn't convert their units, and doesn't state their answer with the correct unit will consistently underperform relative to their actual knowledge. Closing that gap is what Physics Decoded is built to do.
The most common calculation mistakes
- Writing only the final answer without any working shown
- Rearranging the equation mentally without showing the rearrangement step
- Substituting values without converting units first
- Omitting the unit from the final answer
- Using the wrong equation for the question
- Not showing substitution explicitly — jumping from equation to answer
- Using inconsistent units within the same calculation
What parents can do
- When checking a calculation, ask: "Did you write the equation first?"
- Ask: "Did you convert the units before substituting?"
- Ask: "Does your answer have a unit?"
- If marks were lost on a correct method — check whether working was shown at every stage
- Encourage the habit: equation → substitute → rearrange → answer + units. Every time, without exception.
Frequently asked questions
Can a wrong final answer still earn marks?
Yes — where the mark scheme awards method marks. If the equation, substitution and rearrangement are correct and clearly shown, method marks may remain even when the final number is wrong. This is why showing all working is essential, not optional.
Does the equation need to be written if it's given on the formula sheet?
Yes — write it out even if it's provided. This confirms you've selected the correct equation and gives the examiner a clear starting point for awarding method marks. It takes three seconds and protects marks.
How many significant figures should answers be given to?
AQA generally expects answers to be given to the same number of significant figures as the data in the question, or to two or three significant figures unless specified. Giving too many decimal places is not usually penalised, but giving too few can be. When in doubt, match the data given.
Is this relevant for Combined Science students?
Yes — calculation questions appear in Combined Science Physics and the same E-S-R-A method applies. The mathematical skills loading in Combined Science Physics is the same as in separate Physics, making calculation technique equally important for Combined Science students.