A GCSE Maths gap is not simply a topic coloured red. It is a specific part of a topic that breaks under a particular demand. Find it by sampling real questions, showing your working and recording both topic and error cause.

Gather a fair sample

Use three sources:

  1. recent marked class or homework questions;
  2. a short set from a current-board topic or sample resource;
  3. a mixed set where the method is not announced in the heading.

Confirm the specification and tier first. A question outside your course is not evidence of a gap you need to repair.

Build the topic-by-error matrix

Topic/skillKnowledgeMethodReadingAccuracyCommunicationTime/selection
Fractions
Algebraic manipulation
Ratio/proportion
Your topic

Add the question reference, not just a tick. One error may cross two columns; write your leading hypothesis and test it.

Knowledge gap

You cannot state or recognise a needed fact, definition, formula or prerequisite after a genuine attempt.

Method gap

You know relevant facts but cannot select, sequence or justify a procedure.

Reading gap

You miss a condition, unit, diagram feature, command or required form.

Accuracy gap

The plan is valid but arithmetic, signs, copying or calculator entry changes the result.

Communication gap

The answer may be correct, but the recorded method is incomplete or ambiguous for the available marks.

Time or selection gap

You can solve the item later, but the order, decision time or checking routine failed under the conditions.

Test the cause with a contrast

Suppose three simultaneous-equation questions are wrong. Do not immediately relearn the whole topic. Try:

  • a direct elimination item with no context;
  • the same skill in a worded question;
  • an item where substitution is the more efficient choice;
  • an untimed think-aloud attempt;
  • a fresh attempt after checking one worked example.

If the direct item works but the worded one fails, the next task differs from a missing method. If work is correct untimed but not in rehearsal, timing or selection may be involved.

Prioritise by prerequisite, recurrence and value

Choose a repair first when it:

  • blocks several later topics;
  • repeats across more than one question/source;
  • appears in current teaching or a known assessment;
  • can be addressed with a clear next task;
  • has been confirmed rather than guessed from anxiety.

Use the GCSE Maths revision loop to match the repair. The past-paper workflow shows how to sample without wasting a full paper.

Close with a fresh independent retry

Record:

Baseline question and help used:
Cause hypothesis:
Repair completed:
Fresh question:
Result and help used:
Next decision: maintain / more practice / explanation needed.

If the evidence shows a repeated gap that solo repair cannot explain, use the parent decision guide to tutoring alongside a teacher conversation—not as an automatic route to paid support.

Sample the course without testing everything at once

Use three sources:

  1. recent marked classwork or assessment;
  2. a small number of targeted questions for suspected prerequisites;
  3. a fresh mixed sample where the topic is not named.

The targeted question asks “can the learner perform this step?” The mixed sample asks “can the learner recognise when to use it?” Both matter.

Work through a gap diagnosis

A learner loses marks on a percentage-change question.

Visible error: subtracts the values correctly but divides by the new value.

Test competing explanations:

HypothesisSmall check
Does not understand percentage changeAsk the learner to explain what the percentage is relative to
Confuses original and new valuesLabel both values and ask which is the reference
Cannot divide accuratelyGive the correct fraction and check the calculation separately
Misread the direction of changeRestate the context and identify increase/decrease
Memorised a formula without meaningAsk for a diagram or verbal explanation before calculation

After one focused explanation, give a fresh context. If the learner succeeds only when the denominator is pointed out, record prompted success rather than closing the gap.

Prioritise the gap

Score the candidate gap against four questions:

  • Does it block current or upcoming content?
  • Does it recur in more than one piece of evidence?
  • Is it a prerequisite for several topics?
  • Can it be taught and checked at a useful level now?

A small prerequisite can deserve attention before a larger but isolated topic. Do not rank purely by lost marks from one paper.

Distinguish “not taught” from “not learned”

Check the school's current course sequence before calling absent knowledge a gap. Material may not yet have been taught, may belong to another tier, or may not appear in the learner's current specification. A generic online diagnostic can mix these categories.

Copyable gap card

Course/board/tier:
Original task and conditions:
What was secure:
First consequential break:
Competing explanations:
Targeted check:
Teaching/repair:
Fresh independent retry:
Later mixed check:
Status: hypothesis / supported gap / needs teacher clarification

If several attempts suggest a broader prerequisite problem, take the card and work samples to the teacher or tutor. The card supports a conversation; it is not a formal diagnosis.

Sources

  1. AQA — GCSE Mathematics 8300 specification (2026-07-23)
  2. Ofqual — How GCSE and A level marking works (2026-07-23)

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