IGCSE Physics Paper 4: structured questions, show-your-working marks, and where most marks leak

IGCSE Physics rewards a particular kind of fluency. The mark schemes on Paper 4 (and equivalents in the linear and coursework routes) are written by senior examiners who assume candidates will do far more than drop a number into a calculator. A worked numerical question on moments, a qualitative discussion of electromagnetic induction, or a six-mark explanation of transformer action — every one of these carries marks that are awarded only when the right words, the right unit, or the right substitution appear in the right order. IGCSE Physics preparation, at the strongest level, is preparation for that exact moment when a marker holds a red pen above a candidate's script and decides whether the answer in front of them deserves the next mark.

This article focuses on IGCSE Physics Paper 4 — the structured, written component where the bulk of grade differentiation actually happens. We'll look at how the show-your-working marks behave, which topics most reliably leak marks from otherwise well-prepared students, and how a preparation plan can be reshaped around the mark scheme rather than around the textbook. By the end, you should know which kind of practice actually moves a 5 toward a 7 or 8, and which kind feels productive but quietly isn't.

What IGCSE Physics Paper 4 actually tests - and why it is the grade-decisive paper

Most IGCSE Physics candidates sit two written papers in the same examination window. Paper 2 (or Paper 1, depending on the route) is a multiple-choice paper, while Paper 4 is the extended, structured, written paper. For most centres the extended route is the default, and Paper 4 is where the grade boundaries move the most. The reason is structural: Paper 4 is longer, the questions are open-response rather than multiple choice, and a meaningful share of the marks is tied to working, units, and qualitative explanation rather than to a single correct letter.

Paper 4 typically runs for about 1 hour 15 minutes, contains around 80 marks, and is weighted at roughly half of the final grade (the exact weighting depends on the awarding body and the syllabus variant your centre follows). The paper is divided into a small number of structured questions, each of which moves through the syllabus topics in a deliberate order. Within each structured question there are usually two to three sub-parts, and the marks per part range from 1 to 6. The 1-mark parts test recall; the 2- and 3-mark parts test application of a single principle; the 4-, 5-, and 6-mark parts test extended explanation, multi-step calculation, or planning of an experiment.

The mark schemes for Paper 4 are explicit about what earns credit. For calculation questions, examiners publish not only the final answer but the precise acceptable forms of working: the equation to be quoted, the substitution, the intermediate value, the unit, and the final numerical answer to two or three significant figures. For explanation questions, the mark scheme gives an indicative content list — bullet points that summarise the kind of points a candidate would need to make — and a marks-for-quality rule: in a 6-mark question, a candidate typically needs to make around three or four developed points to reach the top band, plus an unambiguous scientific term used in context.

Here is the part most students underestimate: a strong 6-mark explanation is not a long answer. It is three or four carefully chosen statements, each of which names a concept, applies it to the situation in the question, and — where appropriate — links cause to effect. Padding the answer with restated questions, vague hand-waving, or a textbook paragraph copied out of context almost never gains marks and frequently loses them by introducing contradictions. In my experience, the candidates who clean up the most marks in one revision cycle are the ones who learn to write one tight, well-chosen sentence per point and stop.

The show-your-working marks and how they are awarded

The phrase 'show your working' on a physics script is a precise instruction. It means: the marker will read your working line by line, give credit for each correct scientific step, and only then look at the final answer. The marks are awarded independently. If the final answer is wrong but the working shows correct substitution into the correct equation with a correct unit, the candidate will usually collect most of the marks. If the final answer is right but the working is missing, the candidate may collect only one mark (the answer mark), and on some questions may collect nothing at all because the answer mark is conditional on a previous working mark being earned.

This is why practicing numerical questions in IGCSE Physics preparation is qualitatively different from practicing the same calculations in a maths book. In a maths book, the answer is the answer. In Physics, the script is the answer. Three things consistently earn credit:

• The correct equation, written in symbol form — for example, V = IR or P = IV or E = mc². The mark scheme will not accept 'voltage equals current times resistance' as a substitute, except where the question explicitly tells the candidate to use words.
• Correct substitution with units carried throughout — I = V/R, then I = 12 / 4.0, then I = 3.0 A. Carrying the unit at every stage lets the marker see that the candidate knows what each number represents, and it also gives the candidate a free error check at the end.
• A final answer to the correct number of significant figures, with a correct unit — if the question gives data to 2 significant figures, the answer should normally be to 2 or 3. If the data is given to 3, the answer should be to 3. Mismatches in significant figures do not lose marks, but a missing unit almost always does.

A useful drill is to take a single 3-mark calculation from a past paper and rewrite it in the worst possible way: wrong unit, no equation quoted, no substitution, correct final answer. Count the marks. Then rewrite it again in the best possible way: equation quoted, substitution with units, intermediate value, final answer to 2 significant figures with the right unit. Count the marks. The gap between those two rewrites — on a single 3-mark question — is the single most reliable predictor of whether a candidate will move from a grade 5 to a grade 7 on IGCSE Physics Paper 4.

Common pitfalls and how to avoid them in show-your-working marks

• Quoting the wrong form of the equation: W = mg and E = mgΔh are not interchangeable, and a mark scheme will not allow one as a substitute for the other even if the candidate clearly understands the physics. Memorise the form of the equation that appears in the equations sheet and use that exact form.
• Mixing units mid-calculation: candidates frequently convert one quantity to SI but leave another in non-SI, then cancel inconsistently. Pick a unit system at the start of the question and stay in it.
• Skipping the substitution line: jumping from the equation to the final number in one line loses the working mark. Examiners do not infer working.
• Rounding too early: rounding 9.81 to 10, then using 10 in three further steps, can shift a final answer by several percent. Keep at least one extra significant figure through the working and round only at the end.

Six topics where strong students still drop a grade band

Across several years of marking and tutoring IGCSE Physics, a small number of topics reliably separate the grade 5/6 candidates from the grade 7/8/9 candidates. These are not the topics students find hardest in lesson — they are the topics where the mark scheme is most unforgiving about precision. Knowing that a topic is 'hard' doesn't help; knowing exactly which mark the marker is hunting for does.

1. Moments and couples

Moment = force × perpendicular distance from the pivot. Candidates often calculate the moment correctly, then state the answer without a unit (N m, never Nm alone, never J unless the question explicitly frames it as work). The 2-mark 'state and explain' question on the principle of moments trips up candidates who give the principle correctly but then fail to apply it to a non-symmetric case — a seesaw with a child at 1.5 m and an adult at 0.8 m, for example, where the answer is not 'the principle of moments' but a calculated comparison.

2. Electromagnetic induction

The examiner wants three things in any induction answer: a changing magnetic field (or changing flux linkage), a conductor, and relative motion between them. Candidates who say 'magnetism' or 'electricity' without those three elements lose 2 or 3 marks at a time. The direction question (Lenz's law) requires the candidate to describe the induced current opposing the change — not just 'the induced current flows'.

3. Transformer action and the turns ratio equation

The equation V₁/V₂ = N₁/N₂ is on the equations sheet, and most candidates quote it correctly. The mark scheme then wants the candidate to identify that step-up transformers increase voltage and decrease current for a given power, and to link that to the heating effect in the transmission cables. The 5- or 6-mark 'explain why high-voltage transmission is more efficient' question is one of the most reliably lost marks in the whole paper; candidates write a textbook paragraph instead of three or four targeted points.

4. Half-life and radioactive decay graphs

Candidates can almost always read a half-life off a graph when the curve is drawn from the start of the axis. The trap comes when the curve is shifted, when the y-axis is logarithmic, or when the question gives a count rate and asks for the number of half-lives to reach a target. The 3-mark mark scheme will not accept 'about three half-lives' — it wants the candidate to show the calculation, identify the halving sequence, and quote the number.

5. Specific heat capacity and specific latent heat

The equations Q = mcΔθ and Q = mL are on the sheet, but the mark scheme wants the candidate to state which one is being used, then to identify what each symbol represents in the context of the question. The most common loss is mixing the two — using a latent heat equation for a temperature change, or a specific heat equation for a phase change. Unit errors are also common: J, kJ, and J/kg°C all appear in different mark schemes.

6. Pressure in fluids and the manometer equation

P = ρgh and the manometer pressure difference equation are conceptually simple. The mark scheme marks the substitution with a clear density and a clear height difference. The 3-mark pressure-in-a-liquid question is regularly lost by candidates who convert mass to weight correctly but then forget that the height is a difference, not a single depth.

Across these six topics, the pattern is identical. The mark scheme gives credit for: (a) the equation in correct form, (b) the substitution with units, (c) the qualitative or quantitative consequence in the right scientific language. Strong candidates do all three. Average candidates do two. Weak candidates do one. The grade boundary lives in the difference.

Paper 2 versus Paper 4: where your revision time should actually go

Most IGCSE Physics candidates are encouraged to revise 'evenly across the paper'. This is good advice for the first month of revision and bad advice for the last month. By the final fortnight, revision time should be weighted sharply toward Paper 4, and within Paper 4, sharply toward the 4-, 5-, and 6-mark questions. Here's why.

Paper 2 (multiple choice) is a 45-minute, 40-mark paper. Each question is worth 2½ marks in the final weighting. The mark scheme is binary — you get it or you don't. The ceiling on improvement is small: even doubling your accuracy on the hardest five questions on Paper 2 moves the final grade by less than half a band. By contrast, Paper 4 is 80 marks, and a single 6-mark explanation question is worth 7½% of the whole paper. Lifting your mark on one 6-mark question from 3/6 to 5/6 is worth more than lifting your accuracy on every multiple-choice question from 70% to 100%.

There is a tactical consequence here that most candidates miss. In the final two weeks of revision, the highest-return activity is not doing more past papers. It is reading the mark scheme for the past papers you have already done, identifying the 4-, 5-, and 6-mark questions where you lost marks, and writing a model answer to each one in your own words. A model answer is not a copy of the mark scheme's indicative content — it is a 4-to-6-sentence answer that hits every bullet point in the indicative content and uses the scientific vocabulary the mark scheme expects. The act of writing it forces the candidate to convert recognition (which is what past-paper marking builds) into production (which is what the exam actually demands).

A practical weighting for the last 14 days

• Days 1–4: re-mark two complete Paper 4 past papers using the published mark scheme. Do not look at the mark scheme before answering. For every mark lost, classify it as 'recall' (I knew this but forgot), 'process' (I knew the method but applied it wrong), or 'language' (I did not use the right scientific term).
• Days 5–10: pick the 8-to-10 questions where you lost marks for 'language' reasons. Write a model answer to each. Compare each model answer to the indicative content and adjust.
• Days 11–14: one full Paper 2 under timed conditions, then a final review of equations, units, and the most common mark-scheme phrases for 4-mark-or-longer questions.

This kind of plan pulls the candidate away from the comfortable cycle of 'do past paper, mark, feel OK, repeat' and toward the higher-return activity of converting partial knowledge into full marks. For most students, the gap between a grade 6 and a grade 7 sits in 4- and 5-mark questions, not in 1-mark recall.

Reading IGCSE Physics mark schemes the way senior examiners write them

A mark scheme is not a list of right answers. It is a compressed description of what the awarding body has decided to accept on this paper, in this exam window, for this syllabus. Three structural features are worth understanding.

First, mark schemes use 'or' generously. Where two phrasings are acceptable — for example, 'a step-up transformer increases the voltage' and 'the output voltage is greater than the input voltage' — the mark scheme will write both. Candidates who are marking their own work with a too-strict interpretation frequently mark themselves out of marks they would have actually been awarded.

Second, mark schemes use 'reject' precisely. Where a phrasing is wrong — for example, 'a step-up transformer increases the current' (it decreases it for a given power) — the mark scheme will write 'reject increases current' or similar. The reject is there to help the marker, not the candidate, and any candidate who writes the rejected answer loses the mark even if the rest of the answer is correct.

Third, mark schemes use 'independent marks' for calculation questions. The mark for the equation, the mark for the substitution, and the mark for the final answer are usually independent. A candidate who writes the wrong equation but then substitutes correctly into the right equation — which is a common slip — will pick up the substitution mark. A candidate who writes the right equation but substitutes incorrectly will pick up the equation mark. A candidate who writes the wrong equation and substitutes incorrectly may still pick up the final answer mark if the final number happens to match the answer mark scheme. The implication is that a 3-mark calculation is really three 1-mark opportunities, and a candidate who treats it as one 3-mark gamble is leaving marks on the table.

Equations sheet fluency: the silent grade separator

The IGCSE Physics equations sheet — provided to candidates in the exam — is the single most underused resource in most students' preparation. A candidate who has memorised the symbols on the sheet, who knows the unit of each symbol, and who can write each equation in its standard form from memory before the exam starts will answer every calculation question faster and with fewer slips than a candidate who has not.

Three equations are responsible for an outsized share of lost marks:

For each of these, the mark scheme has a mark for the equation, a mark for the substitution, and a mark for the final answer. A candidate who has internalised the form of the equation so deeply that they can write it from memory in five seconds picks up the equation mark reflexively. A candidate who has to think about it loses ten seconds per question and, more importantly, loses confidence on the first calculation, which colours the rest of the paper.

How to use past papers without fooling yourself

Past papers are the most efficient preparation tool available to IGCSE Physics candidates, but only if they are used in a particular way. Doing a past paper, marking it, and putting it in a folder gives a candidate roughly 30% of the available benefit. The other 70% lives in the second pass.

The second pass has four steps. First, re-mark the paper using the published mark scheme, not the mark scheme summary in the textbook. Second, for every mark lost, write a single sentence: 'I lost this mark because I [did not know X] / [wrote Y instead of Z] / [omitted the unit]'. Third, group those sentences by topic — a candidate who finds five lost marks all in 'magnetism and electromagnetism' has a clear revision target. Fourth, write one model answer to the single hardest question from each topic group, and re-write it the next day from memory.

Most candidates do steps one and two and stop. The model-answer step is the one that moves grades. It is also the one that cannot be done well in a group study session; it requires the candidate to sit alone with a blank page and produce an answer that hits every mark scheme bullet, in scientific language, with the right units. A candidate who has done this once per topic in the final two weeks of revision will write faster, more accurately, and with more confidence on exam day than a candidate who has done twice as many past papers but never written a single model answer.

Tactical block: building a paper-4 drill set

A good drill set has 12 questions: two from each of the six high-leakage topics named above. Each question should be a 4-, 5-, or 6-mark question from a recent past paper. The candidate attempts each question under timed conditions — about 1 minute per mark, so a 5-mark question gets 5 minutes. After answering, the candidate marks against the published mark scheme, writes the model answer in their own words, and then re-attempts the model answer from memory 24 hours later. After 12 questions done this way, the candidate has internalised the structure of roughly 60 marks' worth of high-leakage content.

From preparation strategy to exam day: timing, reads, and re-reads

On exam day, three small tactical decisions separate a clean script from a messy one. The first is the read. The first 90 seconds of the exam should be spent reading the front page, the equations sheet reference, and the first structured question's stem — not writing. Candidates who rush into question 1 frequently misread the instruction ('state and explain' versus 'calculate and state the unit') and lose a mark on a question they could have answered.

The second tactical decision is the time-per-question budget. With 80 marks in 75 minutes, the budget is roughly 0.94 minutes per mark. A 6-mark question deserves about 5.5 minutes, a 4-mark question about 3.75, and a 1-mark question about a minute. Candidates who spend seven minutes on a 4-mark question are effectively transferring marks from later questions to earlier ones; the time spent does not earn extra credit beyond the 4 marks already on offer.

The third tactical decision is the re-read. In the final five minutes, the candidate should re-read the questions they flagged as uncertain during the paper and check three things: the unit on the final answer, the number of significant figures, and whether the qualitative answer in a 5- or 6-mark question actually addresses the verb in the question stem ('explain' requires a cause-and-effect link, 'state' requires only a fact, 'describe' requires an account of what happens). Candidates who do this re-read consistently pick up 3 to 6 marks per paper — marks they had already earned in working but had lost in presentation.

What a strong IGCSE Physics preparation plan looks like across a term

A 12-week preparation plan is long enough to cover the syllabus twice and short enough that each week matters. The shape that consistently works for IGCSE Physics candidates is roughly the following.

• Weeks 1–6: cover the syllabus topic by topic, with one Paper 4 structured question attempted per topic at the end of the week. No past papers in this phase; the goal is to build a clean model answer bank of one question per topic.
• Weeks 7–10: full past papers under timed conditions, one per week, with the second-pass mark-up described above. By the end of week 10, the candidate should have done at least three full Paper 4s and two full Paper 2s under exam conditions.
• Weeks 11–12: the model-answer drill set on the six high-leakage topics, one topic per day, with the 24-hour-later recall check. The final two days should be a light review of the equations sheet and the common mark-scheme phrases.

This plan assumes a candidate who has covered most of the syllabus in class and is now consolidating for the exam. For a candidate starting from scratch, the same plan can be compressed into 8 weeks by doing the topic-by-topic work in parallel with the first two full past papers, but the shape stays the same: build a model answer bank early, convert it to marks under timed conditions, then convert marks to grade boundary headroom in the final fortnight.

Conclusion and next steps

IGCSE Physics Paper 4 is the grade-decisive paper for most candidates, and the marks inside it are awarded in a particular, learnable way. A preparation plan built around the mark scheme — particularly around the show-your-working marks, the language of 4- to 6-mark explanations, and the equations sheet — will out-perform a plan built around reading the textbook a second time. The candidates who move from a 5 to a 7 are the ones who write model answers in their own words, who re-mark their own scripts against the published mark scheme, and who re-read their final answers on exam day for units, significant figures, and the right verb in the question stem.

TestPrep İstanbul's IGCSE Physics Paper 4 drill programme is a natural starting point for candidates building this kind of preparation plan, with model-answer templates and timed past-paper sessions organised around the six high-leakage topics above.

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