What "show your working" actually means to an examiner

“Show your working” is said to students perhaps a thousand times between Year 7 and Year 11, and it is almost never explained. Most students end up with one of two wrong interpretations.

The first is that working is insurance: something you produce in case the answer is wrong, so a sympathetic examiner might give you something. The second is that working means writing more, so they fill the space with everything they did, including the parts that went nowhere.

Neither is right. Working is not insurance and it is not volume. It is the evidence for a specific list of marks that the examiner is already looking for.

The examiner is holding a checklist

When your script is marked, the marker is not reading your working as an argument and forming an impression. They have a mark scheme open with a numbered list on it, and they are scanning your page for each item on that list in turn.

For a question worth 4 marks the list might be:

• M1: a correct method to find the volume
• A1: 452 or 452.4
• M1: dividing by the rate
• A1: 7.5

Four things to find. That is the whole exercise. If the M and A notation is unfamiliar, start with what the letters mean. Your working earns marks when it contains those things in a form the marker can recognise, and it earns nothing when it does not, however much of it there is.

Which reframes the instruction completely. “Show your working” does not mean write down what you did. It means make the creditable steps visible on the page.

The three lines that are almost always worth a mark

Across maths and the sciences the same categories of line earn method marks over and over.

The setup line. The formula you are using, with your numbers substituted into it, before you calculate anything. V = πr²h = π × 6² × 4. This one line is the most reliably creditable thing you can write on a maths paper. It is often the entire M1, and it takes four seconds.

The intermediate value. The number you got halfway, before you did the next thing to it. Students calculate this on their calculator, use it immediately, and never write it down. If the scheme has an A1 for that intermediate value, and many do, it is gone. Write the number down.

The conversion or the final operation. Dividing by 100, multiplying by the length, converting cm to m. This is a separate step in the scheme far more often than students expect, and it is frequently done silently in one keystroke.

If you write nothing else, write those.

What does not earn marks

Being honest about this matters, because the advice “show more working” makes some students slower without making them better.

• Rewriting the question. Zero marks, every time.
• Arithmetic you could do in your head. Nobody is awarding a mark for 12 + 8 = 20 laid out in columns.
• Crossed out attempts, unless nothing replaces them. Worth knowing: if you cross something out and do not replace it, examiners are instructed to mark it anyway. If you replace it, the replacement is marked. So cross out a wrong attempt only when you have a better one. Never scribble out your only attempt.
• A wall of unlabelled numbers. If the marker cannot tell which quantity a number is, they cannot match it to the scheme. A number with two words next to it is worth more than the same number alone.

The calculator problem

This is the biggest single cause of unwritten working, and it is not laziness.

On a calculator paper you type a long expression in, press equals, and get a number. Everything in between happened inside the machine. There was no moment where you naturally wrote down the substitution or the intermediate value, because you never handled them.

So the working has to be written deliberately, as a separate act, and the habit is:

1. Write the expression down before you type it in.
2. Type it in.
3. Write the result down.

Three lines, maybe eight seconds. On a question with an M1 for the method and an A1 for the value, that eight seconds is two marks whether or not the rest of the question goes well.

“Show that” and “prove” are different instructions

When a question says show that the answer is 3.5, you have been given the answer. It cannot be what you are being marked on. Every mark is in the journey, and the scheme will typically require the intermediate steps explicitly, sometimes with the note “answer given, working must be seen”.

This is the one place where a correct final answer with no working scores exactly zero. Students who spot that the answer is printed and simply write it down get nothing at all.

Same logic for prove, and for derive in physics. The instruction is telling you where the marks are.

In science, working looks different

In the sciences the equivalent of working is usually one of these:

• The equation before the substitution. Physics schemes routinely award a mark for the correct equation quoted, separately from using it.
• The unit. A standalone B mark on a very large number of calculation questions. It is the cheapest mark on any physics paper and one of the most commonly dropped.
• The named step in an explanation. In biology and chemistry, an explanation is marked as a chain: each link is a mark. “The rate increases” is one point; “because particles have more kinetic energy” is another; “so more collisions exceed the activation energy” is a third. Missing the middle link costs the middle mark even when the conclusion is right.

The test to run on your own past paper

Take a question you got wrong, cover your final answer, and hand your working to someone doing the same subject. Ask them one thing: can you tell what I was trying to do?

If they can, your working is doing its job and the marks are recoverable. If they cannot, then neither could an examiner, and the marks were not lost on the maths. They were lost on the page.

That is worth internalising, because the second kind of loss is by far the easier one to fix. It is not a gap in what you know. It is a habit, and it can be changed in a fortnight.

What this looks like in a classroom

The efficient version of this lesson is not the phrase at all. Put a real mark scheme in front of a class with two scripts: one with the right answer and no working, one with the wrong answer and the full method. Let them mark both. The scores come out backwards from what everyone expects, and that is the lesson.

Marky records the same distinction, so a student reads “M1 awarded, A1 refused because the answer was not evaluated” instead of a cross. See how a marked paper looks.