The 5 Mistakes AQA Maths Examiners Flag Every Year — and How to Stop Making Them

1. Not showing working

This is the single most common way students lose marks they could have kept. AQA mark schemes award method marks (M marks) for correct working, even if the final answer is wrong. If you perform a calculation mentally or on a calculator and write only the answer — and that answer is wrong — you score zero on the question. If you had shown the correct method, you would have scored at least one mark. Examiners cannot award marks for work they cannot see. Write every step, even on questions that feel straightforward.

2. Rounding too early

Early rounding is one of the most penalised errors in multi-step questions, particularly trigonometry, bounds, and area and volume calculations. If you round an intermediate value mid-calculation — say, rounding sin(63°) to 0.891 and then using that in the next step — the rounding error compounds. AQA examiners specify that intermediate values should be kept to at least four significant figures (or held in your calculator memory) until the final step, where you round to the degree of accuracy the question requests. A final answer of 12.4 instead of 12.3 due to early rounding will cost the accuracy mark.

3. Missing units

For questions asking for a measurement — area, perimeter, volume, mass, cost — the unit is part of the answer. Writing "12.3" when the answer is "12.3 cm²" will lose the final mark if the mark scheme requires the unit. This applies to compound measures too: speed in m/s, density in g/cm³, pressure in N/m². Set yourself a habit: read the question's units, underline them, and write the unit next to your final answer before you move on.

4. Sign errors in algebra

Sign errors — particularly when expanding brackets, collecting like terms, or rearranging equations — are the most frequent source of incorrect answers on algebra questions. Common slip: expanding (x − 3)(x + 2) and writing x² − x − 6 instead of x² − x − 6 is correct, but expanding (2x − 3)² as 4x² − 9 instead of 4x² − 12x + 9 is a very common mistake. Write each expansion step separately. Do not try to combine two steps mentally. Double-check signs whenever you bring a term across the equals sign.

5. Not re-reading the question before writing the answer

AQA examiner reports use almost identical language every year: students must "read, read and read again". The most common version of this mistake is solving the correct equation but answering a different question — finding x when the question asks for the perimeter, or finding the probability of one event when it asks for both events combined. Before you write your final answer, re-read the last sentence of the question. Does your answer actually answer what was asked? Is it in the right form (e.g., a fraction, a ratio, a specific number of significant figures)?

The exam habit that prevents all five

Practice a three-step check on every question under timed conditions: (1) show the method before calculating, (2) keep full precision until the final step, (3) re-read the question and check your answer includes the right form and units. This adds 10-20 seconds per question but is worth it — each of these five errors costs between 1 and 3 marks on questions you already knew how to do.