GCSE Maths Foundation · AQA · Maths
The five GCSE Maths Foundation mistakes examiners flag every series
Every AQA GCSE Maths Foundation mark scheme highlights the same handful of misconceptions in its examiner's report — and the same handful resurface in the next series, then the one after that. The patterns are durable. They aren't carelessness; they're predictable shortcuts the brain takes when maths is read like English.
Below is the full set as of the current AQA specification. Each page names the misconception, explains why it happens, shows a worked example, and gives you a thirty-second technique to fix it. If you want to know which ones you personally fall for, the free 10-minute diagnostic will tell you.
Which ones are costing you marks?
The 10-minute diagnostic tests for all five with AQA-style items. You get a grade-band prediction and a list of which patterns to fix first. Free, no signup, anonymous.
Confusing percentage change with percentage of, reversing direction on a reverse-percent, or summing percentages across multiple stages.
Longer-is-bigger reasoning (0.45 > 0.6), ignoring the decimal point, or misplacing it in arithmetic results.
Treating a fraction as two integer streams — adding numerators and denominators independently.
Scaling a ratio by addition (2:3 → 4:5 by adding 2 to each side) instead of multiplying both parts by the same factor.
Bigger-perimeter-means-bigger-area intuition, using diameter as radius, or treating area and volume as linearly scaled.