IGCSE Physics show your working 2026: The complete mark-saving guide

In IGCSE Physics, showing your working means presenting each calculation clearly enough for the examiner to see the formula, substitution, solving process, and final unit. A structured method such as F-S-S-U helps students secure method and accuracy marks even when a small arithmetic error occurs. Clear working is especially important in multi-step calculations, where Cambridge may apply Error Carried Forward when the later method is correct.

This guide explains how to show your working effectively in Cambridge IGCSE Physics 0625 and avoid losing marks through incomplete calculation steps.

How to show your working in IGCSE Physics to maximise marks

The F-S-S-U framework is the single most reliable method for structuring every calculation in IGCSE Physics ^[1]. Drawing on years of experience at Times Edu coaching students through Paper 3 and Paper 4, this four-step layout consistently produces higher marks than any other approach.

F stands for Formula. Write the raw algebraic formula exactly as it appears in the Cambridge syllabus. Do not rearrange it yet. Do not insert numbers. Simply write: F = m × a or P = IV.

S stands for Substitution. Replace each letter with the numerical value given in the question. Write this as a separate line, directly underneath the formula. This is the line that earns your Method (M) mark.

S stands for Solved Answer. Perform the arithmetic, rearrange if necessary, and write the final numerical value rounded to 2 or 3 significant figures. Never copy a raw calculator decimal such as 0.41666… Onto your paper.

U stands for Unit. Attach the correct SI unit to your answer, written with the correct capitalisation. The unit is almost always worth a dedicated mark or is bundled into the Accuracy (A) mark.

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Why showing working is critical in IGCSE Physics calculations

The Cambridge IGCSE Physics mark scheme uses three distinct mark types on calculation questions: Compensatory (C) marks, Method (M) marks, and Accuracy (A) marks. Each type is awarded at a different stage of your written response.

A Compensatory mark is awarded simply for writing down a correct formula, regardless of everything that follows. A Method mark is awarded for correct substitution of values into that formula, again regardless of the final answer. An Accuracy mark requires both the correct numerical answer and the correct unit.

This structure means that a student who makes a single arithmetic error can still earn two out of three marks on a three-mark question, but only if they have written their steps down clearly. A student who skips straight to the answer and makes that same error earns zero.

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How much working is enough for each question type in IGCSE Physics

A common mistake we see at Times Edu is students writing either too little or too much. Too little risks losing method marks. Too much wastes precious exam time. The right amount depends on the mark allocation shown in brackets beside each question.

For a 1-mark question, you typically need only the answer and its unit. No formula or substitution is required because there is no method mark to award.

For a 2-mark question, you need at minimum a formula or substitution line plus the final answer with unit. Examiners are looking for evidence that you understand which physical relationship applies.

For 3-mark and 4-mark questions, the full F-S-S-U layout is non-negotiable. These questions are explicitly designed to award separate marks for each stage of the working process.

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How to present working for multi-step Physics calculations in IGCSE

Multi-step calculations appear frequently on Paper 4 and occasionally on Paper 3. These questions require two or more separate calculations in sequence, where the output of one step feeds into the next.

One critical detail often overlooked is that each step in a multi-step problem carries its own set of M and C marks. Treat each step as a completely independent calculation and apply the F-S-S-U layout to each one separately.

If you carry forward a wrong answer from Step 1 into Step 2, Cambridge’s “own figure rule” (often abbreviated as ECF, meaning Error Carried Forward) protects you. You will not be penalised twice for the same error, provided your method in Step 2 is visibly correct.

How to lay out a two-step calculation:

• Label each step clearly: “Step 1:” and “Step 2:” on separate lines.
• Complete the full F-S-S-U layout for Step 1 before moving to Step 2.
• When substituting into Step 2, use the answer you calculated in Step 1, even if you suspect it may be wrong.
• Never skip writing the intermediate answer, because that value is what triggers the ECF protection.

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How to show equation selection and substitution clearly in IGCSE Physics

Selecting the correct equation is the intellectual core of every IGCSE Physics calculation. However, even perfect equation selection earns zero marks if it is not written down.

In our experience working with international students preparing for Cambridge assessments, the most common failure point is not knowing the wrong formula. It is writing the correct formula mentally, skipping that line on paper, and then receiving no Compensatory mark because the examiner has no evidence of it.

Write the formula first, always. Even on the simplest questions where the answer feels obvious, the written formula is your insurance policy against arithmetic errors. Think of it as signing your name before submitting a document: It confirms your intent to the reader.

Substitution discipline matters equally. When you replace algebraic symbols with numbers, write the numbers in the same position as the symbols. If the formula is v = u + at, your substitution line must read v = 0 + (2.5)(4), not v = 2.5 × 4. The position of each value tells the examiner which quantity you have assigned it to.

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When crossing out working helps or hurts you in IGCSE Physics

Students frequently ask whether they should cross out working that they believe is wrong. The answer depends entirely on what you are crossing out.

If you cross out a complete, incorrect attempt and replace it with a fresh F-S-S-U layout, the examiner will mark only your final attempt. This is the correct strategy. Examiners are instructed to mark the response the candidate has chosen to keep, not the response the candidate has abandoned.

However, if you cross out a partially correct attempt and your replacement attempt is entirely wrong, you have actively destroyed marks that were available to you. A common mistake we see is students crossing out a line that contained a correct formula simply because they lost confidence during the exam.

The safest rule: Never cross out a formula line unless you are replacing it with a different, correct formula. A method mark awarded for a formula cannot be taken away from you mid-question, but it can be erased if you physically remove it from the page.

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Common working presentation mistakes that cost marks in IGCSE Physics

Drawing on years of experience at Times Edu reviewing student scripts and mark scheme analyses, these are the presentation errors that appear most consistently across exam sessions.

Mistake 1: Writing units inside the substitution line. When students write F = 0.50 kg × 4.0 m/s², the examiner must check whether the units are correct before awarding the M mark. This creates ambiguity and wastes your time. Write only numbers in the substitution line. The unit belongs on the final answer line only.

Mistake 2: Rounding too early. If a question requires two steps and you round your Step 1 answer before using it in Step 2, your Step 2 answer will be slightly off. Cambridge mark schemes allow a small range of acceptable values, but premature rounding can push your answer outside that range. Carry all significant figures through intermediate steps and round only your final answer.

Mistake 3: Writing the correct answer with the wrong unit. An Accuracy mark in Cambridge Physics typically bundles the numerical value and the correct unit together. Writing I = 0.42 when the answer requires I = 0.42 A may cost you the entire Accuracy mark on that question.

Mistake 4: Using non-standard symbols. Cambridge mark schemes reference specific symbols. Writing m when you mean mass and M when you mean something else is fine, but inventing your own symbols without defining them risks confusing the examiner. Stick to syllabus notation.

Mistake 5: Compressing multiple steps onto one line. Writing F = 0.50 × 4.0 = 2.0 N on a single line removes the distinct formula step. If your arithmetic is wrong and you have no separate formula line, the examiner has no standalone evidence of the formula to award the C mark.

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Frequently asked questions

Conclusion

At Times Edu, our consultants and subject tutors work one-on-one with students to build exactly these habits through structured exam practice, mark scheme analysis, and personalised feedback. If your child is preparing for IGCSE Physics and you want a clear academic roadmap tailored to their current level and target grade, contact Times Edu today to schedule a personalised consultation. The right strategy, applied consistently, is what turns potential into results.

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