Cambridge International · study method
How to find your weak topics from past papers
Log every mark you lose, tag each one to the syllabus topic it tests, and total the lost marks by topic across at least three papers. Then weight each topic by how much of the paper it usually carries. The topics at the top of that list are where revision returns the most marks.
A single paper is not enough: a topic can be missing from one paper and worth 10% of the next. Three papers start to show a pattern; five make it reliable.
Updated 1 October 2026
Written by the Quanta team. How Quanta marks papers
1. Keep a lost-mark log
After marking each paper strictly against its scheme, write one line per lost mark: the paper, the question, how many marks, the topic, and why it went — method not shown, accuracy, missing reason, or not attempted. How to mark strictly.
2. Tag each mark to the syllabus
Use the syllabus’s own topic list, not the textbook chapter, so your log matches how Cambridge organises the exam. The current syllabus for each subject:
3. Total it and weight it
Add up the lost marks per topic, then look at how much each topic is worth. A topic you lose 5 marks on that carries 9% of the paper beats one you lose 5 marks on that barely appears. Cambridge does not publish topic weights, so Quanta counts them from real papers: IGCSE Maths 0580, A Level Maths 9709, A Level Economics 9708, AS Chemistry 9701 and A Level Business 9609.
An example: a student after three 9709 Paper 1s (the lost marks are illustrative; the topic shares are measured across 42 real papers):
| Topic | Marks lost | Share of Paper 1 | On papers |
|---|---|---|---|
| Solve trig equations | 7 | 5.2% | 39/42 |
| Arc length and sector area | 6 | 8.9% | 42/42 |
| Discriminant | 5 | 3% | 25/42 |
| Binomial expansion | 2 | 6.5% | 41/42 |
Trig equations and arc length come first: the most marks lost, on topics that appear on almost every paper. The discriminant is next — five marks lost, but a smaller share, on fewer papers. Binomial expansion carries as large a share as trig equations but costs this student little, so it waits.
4. Separate slips from gaps
A slip is a mark lost on something you can do — a sign, a copying error, a rushed final line. A gap is a mark lost because you could not do it. Fix gaps first: slips shrink with care and time checks, gaps only with practice. If most of a topic’s lost marks are slips, it moves down the list.
5. Retest, then repeat
Practise the top topic with past-paper questions on just that topic, then sit a full paper and log it again. The list should change. If a topic stays at the top after two rounds, change how you are learning it, not just how much.
Quanta keeps this log for you: every question is mapped to its mark scheme and tagged to its syllabus skill, so lost marks build a ranked list on their own, with slips counting for less. How it works.
Common questions
How many past papers do I need to find my weak topics?
At least three; five is better. One paper can leave out a topic entirely, so a single paper describes that paper, not you.
Should I revise my weakest topic or the most common one?
The one where both are true. Rank by marks lost, then favour topics that carry a large share of the paper — that is where the next hour returns the most.
Practise real Cambridge past papers against real mark schemes
Quanta has real Cambridge A Level Maths 9709 past-paper questions, broken into skill checkpoints, marked criterion by criterion the way examiners mark — and it tracks which skills you’re missing. Free for individual students.
Start practising free