GCSE Maths: What 'Showing Your Working' Actually Means — and Why It Affects Your Grade
When a GCSE Maths examiner marks a question worth three or four marks, they are not just looking at the final answer. They are looking at the method the student used to get there. If that method is written down clearly, the student can pick up most of the marks even when the final answer is wrong. If it isn't, a single slip can cost every mark on the question.
This is what teachers mean when they say "show your working". It is not a tidiness rule. It is the mechanism by which partial credit is awarded, and it is one of the most reliable ways for students to protect marks they have genuinely earned.
How method marks actually work
GCSE Maths questions worth more than one mark are usually broken down behind the scenes into a combination of method marks (M), accuracy marks (A) and sometimes B marks for specific correct statements. All the main exam boards — AQA, Edexcel, OCR and WJEC Eduqas — use variations of this system.
A rough example: a four-mark question might award:
- 1 mark for setting up the correct approach
- 1 mark for a correct intermediate calculation
- 1 mark for a further correct step
- 1 mark for the final correct answer
If a student writes only the final answer and it is wrong, they score zero out of four. If they show each step and make an arithmetic slip near the end, they can still score three out of four. Across a full paper, this difference frequently separates one grade from the next.
Method marks are also "follow through" in many cases. If an earlier mistake is carried correctly through the rest of the working, the later method marks can still be awarded. That only works if the later working is actually there to be marked.
What counts as sufficient working
Students often ask how much they need to write. A useful rule of thumb: an examiner should be able to follow the reasoning without guessing.
For a multi-step question, that usually means writing down:
- The equation, formula or relationship being used
- The numbers substituted in
- Each intermediate result, labelled where helpful
- The final answer, with units if required
Here is a short worked example. Suppose a Higher tier question asks for the area of a sector with radius 8 cm and angle 60°.
A student who writes only 33.5 cm² has given the examiner nothing to mark except the final number. If it is wrong, that is zero marks.
A student who writes:
Area = (θ/360) × π × r²
= (60/360) × π × 8²
= (1/6) × π × 64
= 33.5 cm² (3 s.f.)
has shown the formula, the substitution, a simplified intermediate step and a final answer. Even if they mistype 64 as 46 on the calculator and get the wrong number, they will still earn the method marks for the formula and substitution.
The same principle applies on Foundation tier. A percentage question, a ratio problem or a question about compound measures all have intermediate stages that can be marked if written down.
The calculator-only trap
The most common way students lose easy marks is by doing a whole question on their calculator and writing only the final number.
Modern scientific calculators can handle long chains of operations in one go. A student can type an entire expression in, press equals, and copy the result. If the result is right, they get full marks. If it is wrong — because of a mistyped digit, a missing bracket or an order-of-operations error — they get nothing, because there is no written method for the examiner to credit.
This is particularly costly on:
- Compound interest and growth or decay questions
- Trigonometry and Pythagoras problems
- Standard form calculations
- Questions involving fractions typed into the calculator
- Any "show that" question, where a stated answer is given and the marks are entirely for the method
On "show that" questions, writing the given answer with no working scores zero by definition. The entire question is about the process.
A habit students can adopt immediately
The single most useful habit is this: for every question worth two marks or more, write at least one line of working before the final answer.
That line should contain either the formula being used, the calculation being performed, or the relationship between the quantities in the question. It takes a few seconds and it protects marks on dozens of questions across a paper.
A slightly fuller version of the habit looks like this:
- Read the question and identify what is being asked.
- Write the formula or set up the calculation on the page before touching the calculator.
- Substitute the numbers in on paper.
- Do the arithmetic on the calculator.
- Write the result, then the final answer with units.
Students who already do this on hard questions often skip it on questions they find easy. Those are precisely the questions where a careless slip is most likely, and where written working is most likely to rescue the marks.
How parents can help without knowing the maths
Parents who are not confident reviewing maths themselves can still check for the habit rather than the content. When looking at past paper practice, it is reasonable to ask:
- Is there any written working for questions worth two or more marks?
- Can you see a formula or a calculation, not just an answer?
- On "show that" questions, is there a clear chain of steps?
If the page is mostly blank with answers in the margin, the habit isn't there yet, regardless of whether the answers happen to be right.
Students often need someone to point out, in the moment, where working would have saved marks on a specific question. That is one of the things one-to-one tuition is useful for: a tutor marking live can show exactly which line of working the examiner would have credited and which they would not. At Luminary Tutoring, this kind of exam-technique feedback runs alongside the mathematical content in each lesson, and the recording lets students revisit the explanation when they next tackle a similar question.
The habit itself, though, costs nothing and can be adopted from the next piece of homework onwards. Over a two-year GCSE course, that is a very large number of marks protected for the sake of a few extra lines on the page.