If you have ever thought “my answer was basically right” and still lost half the marks, you have met Cambridge method marking. On papers like 9709, examiners rarely award a single blob of points for a number at the bottom of the page.

The three letters you see everywhere

Mark	Meaning	Typical student mistake
B1	Independent mark — often a correct formula, statement, or graph feature	Forgetting to write the definition domain
M1	Method mark — correct approach even if arithmetic slips	Right idea, wrong substitution shown
A1	Accuracy mark — correct value or expression	Copy error from calculator
A1ft	Accuracy follow-through — correct based on your earlier error	Not shown because you restarted

ECF (error carried forward) means later marks can still be earned if your method stays consistent with an earlier slip — but only if your working is visible.

A miniature example (integration flavour)

Suppose a scheme shows:

M1 for recognising ∫ requires substitution or parts
A1 for the integrated form
A1 for the evaluated definite answer

If you jump straight to a number with no method, you may get zero even when the number matches the mark scheme final answer. Examiners reward visible reasoning.

How to self-mark maths without cheating

Cover your final answer and mark line by line.
For each M mark, ask: “Is this step valid on its own?”
For each A mark, ask: “Is this exact — or ft from my previous line?”
If you used a calculator, ensure enough working remains for Cambridge standards (your teacher’s policy + the specimen mark scheme style).

Whole-paper maths habits

On full papers, marks cluster where students rush:

Quadratics and discriminants — sign errors cost M1 and A1 together.
Trigonometry — degrees/radians and range restrictions lose B marks.
Statistics — wrong n in variance formulas loses method before accuracy.

When you mark a whole past paper, note which types of M marks you miss repeatedly — that is your revision list, not “I am bad at maths.”

When to move on vs redo

Redo if you lost a method mark — the skill is not secure.
Move on if you lost only accuracy once — drill arithmetic separately.
Ask for a second marker if you disagree with the scheme’s follow-through — fresh eyes help.

Takeaway

B1/M1/A1 is not bureaucracy. It is the examiner telling you which skill each mark buys. Mark schemes are the specification written in points — learn that language and your past paper scores stop feeling random.