GCSE Maths: How to Tell Whether Your Child Has a Genuine Gap or Just an Exam Technique Problem

A disappointing mark on a Maths paper usually means one of two things: your child does not understand the topic, or they do understand it but something went wrong when they tried to show it on paper. These are very different problems and they need very different responses.

Knowing which one you are looking at saves a lot of wasted revision. A child who keeps drilling quadratic equations they already understand will not improve if the real issue is that they are running out of time, misreading questions or skipping method marks. Equally, polishing exam technique will not fix a genuine misunderstanding of, say, how to rearrange formulae.

Here is how to tell the difference using the work your child already has.

Start with the mark scheme, not the mark

Most GCSE Maths questions award marks for method as well as the final answer. A six-mark question might award four or five marks for the working and only one or two for the answer. That matters because:

• A child can get the right answer and still lose marks for missing working.
• A child can get the wrong answer and still earn most of the marks if their method is sound.
• The pattern of lost marks tells you where the problem actually is.

If your child's school has returned a mock paper, ask for the mark scheme too. Exam board mark schemes for past papers are freely available on AQA, Edexcel, OCR and WJEC/Eduqas websites. Sit down with your child and go through two or three questions where they lost marks. You are looking for a pattern, not a verdict on a single question.

The four questions to ask

For each question where marks were lost, work through these in order:

1. Did they understand what the question was asking? Ask your child to read the question aloud and explain it in their own words before looking at their answer. If they cannot, the problem started before any Maths happened.
2. Did they know a method that could have worked? Not necessarily the one in the mark scheme — any valid method. If they can now explain a correct approach without help, the knowledge is there.
3. Did they write enough working to earn the method marks? Look for whether the examiner could follow their thinking. A correct answer with no working often loses marks on multi-mark questions.
4. Did they make an arithmetic or copying slip? Writing 42 instead of 24, dropping a minus sign, or copying a number incorrectly from one line to the next.

The answers to these four questions sort most mistakes into one of two categories.

Signs of a genuine conceptual gap

• Your child cannot explain the method even after reading the question carefully.
• They attempt the wrong type of calculation — adding when they should multiply, using the wrong formula, treating a percentage decrease as a percentage of the new value.
• The same type of mistake appears on several different questions on the same topic.
• Looking at the worked solution produces an "I've never seen that" reaction rather than "oh, of course".
• They can do a simple version of the topic but fall apart as soon as it is combined with anything else — for example, they can solve a linear equation but not when it comes from a geometry problem.

Conceptual gaps need teaching, not just practice. Doing more questions on a topic you do not understand tends to cement the misunderstanding.

Signs of an exam technique problem

• The method is right but the final answer is wrong because of an arithmetic slip.
• Working is sparse or missing, so marks are lost even when the answer is correct.
• They misread the question — found the perimeter instead of the area, gave the answer in cm instead of m, or solved for x when the question asked for y.
• They ran out of time, leaving several questions at the end blank or barely attempted.
• They spent far too long on one difficult question and never reached easier marks later in the paper.
• They did not use the formula sheet, or they did not notice information given in an earlier part of a multi-part question.
• Their answer is unreasonable — a negative length, a probability greater than one — and they did not notice.

These problems are usually faster to fix than conceptual gaps, but they do need deliberate practice under timed conditions, not just more untimed homework.

What to look for in the written working itself

Open your child's exercise book or mock paper and look at the layout, not the Maths. Ask yourself:

• Can you follow the working from top to bottom without jumping around?
• Is each line a reasonable next step from the one above?
• Are units, signs and brackets written clearly?
• Is the final answer underlined, boxed or otherwise identifiable?
• For a geometry or statistics question, is there a labelled diagram or table?

You do not need to understand the Maths to answer any of these. Messy, disorganised working is a strong predictor of lost method marks, and it is one of the easiest things to improve.

A worked example of the diagnosis

Suppose a Higher tier student loses marks on this question: "A bag contains 5 red and 3 blue counters. Two counters are taken without replacement. Find the probability that both are red."

• If they wrote 5/8 × 5/8, they do not understand "without replacement". That is a conceptual gap in conditional probability.
• If they wrote 5/8 × 4/7 and got 20/56 but did not simplify, they understand the topic and have lost a presentation mark.
• If they drew a tree diagram with correct probabilities but then multiplied the wrong pair of branches, that is a reading or care error.
• If they left the question blank because they ran out of time, the problem is pacing, not probability.

Four different diagnoses, four different responses. Same question, same lost marks.

When to get a second opinion

If you have gone through a mock paper and genuinely cannot tell whether a mistake is conceptual or technical, that is normal. Some mistakes look like one and are really the other. A child who writes nothing on a question might not understand it, or might have panicked, or might have skipped it intending to come back.

Your child's Maths teacher is the first person to ask. A short conversation at parents' evening, or an email with a specific question attached, usually gets a useful answer.

A one-to-one lesson can also do this diagnosis efficiently. Sitting with a student, asking them to talk through their working on a handful of lost-mark questions and probing where the reasoning breaks down usually reveals the pattern within a lesson or two. At Luminary Tutoring, our GCSE Maths lessons often begin exactly this way — with a marked paper and a conversation — before any new teaching happens, because the right next step depends entirely on what the real problem is.

Whichever route you take, the useful next step is the same: pick one recent paper or piece of marked homework, go through the lost marks with the four questions above, and write down what you find. The pattern will usually be clearer than you expect, and it will tell you what kind of practice is actually worth doing.