How to Read Official IGCSE Mark Schemes

Q: What does M1 mean in an IGCSE mark scheme?

M1 is a method mark. It is awarded for using a valid method applied to the problem, provided some relevant working is shown. Accuracy marks that follow usually depend on earning the method mark.

Q: What is the difference between A1 and B1?

A1 is an accuracy mark, normally dependent on a preceding method mark. B1 is an independent mark awarded for a correct result or statement that does not depend on method marks.

Q: What does ft or FT mean?

FT means follow through after error. The examiner awards the mark based on the candidate’s earlier (possibly incorrect) value, provided the subsequent method is correct.

Written by Jevin Chew · 2 September 2026 · Last updated 2 September 2026 · ~14 min read

Official Cambridge IGCSE mark schemes look dense at first glance: columns of answers, partial marks, and a string of codes such as M1, A1, B1, ft and oe. Once you understand what each symbol means, those documents become one of the most powerful revision tools you have. This guide explains the standard Cambridge annotations used across Mathematics and many science subjects, and shows you how to use them to mark your own past papers accurately.

Quick takeaway: M marks reward the correct method (even if the final number is wrong). A marks reward accuracy and usually depend on the method. B marks are independent. Follow-through (ft) protects later marks when an earlier calculation is wrong. Learning these codes stops you from over-penalising yourself when you self-mark.

1. Why mark schemes matter more than answer keys

A simple answer key only tells you whether the final number is right. A Cambridge mark scheme tells you where the marks are earned. In a four-mark question structured as M1 A1 M1 A1, an arithmetic slip in the first calculation typically costs only the first accuracy mark. If you continue correctly with your (wrong) intermediate value, you can still collect the remaining method and accuracy marks through follow-through. Students who understand this write clearer working and recover more marks under exam conditions.

Mark schemes are published by Cambridge Assessment International Education for each component and series. They are written for examiners, so the language is compact and technical. The same core system appears in Mathematics (0580 / 0980), Additional Mathematics, the sciences and many other subjects, with only minor variations.

2. The three main types of mark

M – Method mark

An M mark (M1, M2, …) is awarded for a valid method applied to the problem. Relevant working must be seen; a correct final answer with no method usually scores M0. When a question has several method steps, the M marks are in principle independent unless the scheme says otherwise. The notation dep (dependent) indicates that a later M or B mark can only be awarded if an earlier mark has been earned.

A – Accuracy mark

An A mark (A1, A2, …) is given for a correct answer or intermediate step correctly obtained. For accuracy marks to be awarded, the associated method mark must normally be earned or clearly implied. If the scheme shows “A1 cao”, the exact answer is required and follow-through is not allowed on that mark.

B – Independent mark

A B mark (B1, B2, …) is awarded for a correct result or statement that does not depend on method marks. Typical examples include reading a value from a graph, stating a definition, or giving a correct numerical answer that does not require multi-step working. B marks stand alone.

3. Common abbreviations and what they mean

These abbreviations appear repeatedly in Cambridge IGCSE mark schemes. Memorising them removes most of the mystery.

Abbreviation	Full form	Meaning
M1 / M2	Method mark	Credit for a valid method; working must be seen.
A1 / A2	Accuracy mark	Correct answer or intermediate result; usually depends on M.
B1 / B2	Independent mark	Correct statement or value independent of method.
cao	Correct answer only	Exact answer required; no follow-through on that mark.
ft / FT	Follow through	Award the mark using the candidate’s earlier (possibly wrong) value if the later method is correct.
oe	Or equivalent	Any mathematically equivalent form, fraction or expression is acceptable.
dep	Dependent	This mark can only be awarded if a previous specified mark has been scored.
isw	Ignore subsequent working	Once a correct answer is reached, later incorrect work does not cancel the mark.
soi	Seen or implied	The method or value does not have to be written explicitly if it is clearly used.
SC	Special case	An alternative route or partial credit defined for a specific wrong or incomplete approach.
nfww	Not from wrong working	The answer must come from correct working; a fortuitous correct answer from wrong method scores zero.
awrt	Answers which round to	Accept values that correctly round to the stated figure.
rot	Rounded or truncated	Allow rounding or truncation as specified.
www	Without wrong working	Similar idea to nfww: the result must not arise from incorrect earlier steps.

In some science mark schemes you may also meet E1 (explanation), U1 (units) or G1 (graph feature). The principle is the same: each code tells the examiner exactly what must be present for that mark.

4. How follow-through (ft) works in practice

Follow-through is the feature that most students under-use when self-marking. Suppose a five-mark question is structured as:

M1 A1 M1 A1 ft A1 ft

You make an arithmetic error in the first calculation. You still earn the first M1 (method was correct) but lose the first A1. If you then apply the correct second method to your wrong intermediate value and continue carefully, the examiner awards the later M1 and the two follow-through accuracy marks. One slip costs one or two marks instead of the entire question. This only works if your working is clear enough for the examiner to see what value you used at each step.

When the scheme writes “their x” or “FT their diagram”, it is instructing the marker to follow the candidate’s own earlier result.

5. How to use a mark scheme for self-study

Sit the past paper under timed conditions without looking at the scheme.
Open the official mark scheme and work question by question.
For each part, ask: Did I show a method that matches the M criteria? Is my final (or intermediate) value correct for the A mark? Is there an independent B mark I can claim?
Apply follow-through honestly: if an earlier number was wrong but later steps are correct, award the ft marks.
Note any SC (special case) routes — these often reveal alternative methods Cambridge accepts.
Record the marks you lost and the reason (missing method, arithmetic, incomplete statement). Patterns in those losses become your next revision targets.

Be stricter with yourself than a generous teacher might be. The goal is to discover gaps, not to inflate a practice score.

6. Practical tips that improve both marking and exam technique

Show every method step. M marks require visible working. A correct answer alone often scores only the accuracy marks if any, and sometimes zero.
Write intermediate values clearly. This makes follow-through possible for the examiner and for your own later checking.
Watch for “cao”. When the scheme insists on the correct answer only, an equivalent form or a follow-through value will not score that particular mark.
Accept “oe”. Equivalent fractions, simplified expressions or alternative algebraic forms are usually fine unless cao is specified.
Read the partial marks column. It often lists exactly what earns each M or B mark (for example “M1 for 180 − 2 × 43”).
Use special cases. SC marks reward common alternative approaches. Knowing them can turn a near-miss into partial credit.
Ignore subsequent working (isw). Once you have reached a correct answer, further messy algebra does not cancel the mark already earned.

7. A short worked illustration

Imagine a two-mark question whose scheme reads:

Answer: 1.5 oe
Marks: 2
Partial marks: M1 for 8x = 7 + 5 or equivalent rearrangement; A1 for 1.5

If a student writes the correct rearrangement but then divides wrongly and obtains 1.6, they still receive M1. The A1 is lost. If the scheme had included “A1 ft”, the wrong numerical answer obtained from correct later working might still score; here it does not, because the accuracy mark is tied to the exact value. Understanding that distinction prevents both over-marking and under-marking in practice papers.

8. Subject variations

The M / A / B framework is most explicit in Mathematics. In Biology, Chemistry and Physics the schemes often list acceptable points or phrases and use “allow”, “ignore” or “do not accept”. The underlying idea is identical: the scheme defines the minimum that must be present for each mark. Always read the front pages of the mark scheme for that component; they contain the official list of abbreviations used in that paper.

After you have marked a past paper
Convert your raw component totals into weighted syllabus marks and see how they sit against recent grade thresholds.

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Frequently asked questions

What does M1 mean in an IGCSE mark scheme?

M1 is one method mark. It is awarded for a valid method applied to the problem when relevant working is shown. Later accuracy marks usually depend on it.

What is the difference between A1 and B1?

A1 is an accuracy mark that normally requires the associated method mark. B1 is an independent mark for a correct result or statement that does not depend on method.

What does ft or FT mean?

Follow through after error. The examiner uses the candidate’s earlier value (even if wrong) provided the subsequent method is correct.

Can I get marks for a correct answer with no working?

Usually only accuracy or independent marks, and sometimes none. Method marks require visible working. Always show your method.

Where do I find official mark schemes?

On the Cambridge International website (or through your school/centre) alongside the corresponding past paper for each component and series. Use only the official published versions.

Mark scheme conventions are set by Cambridge Assessment International Education and can vary slightly by syllabus and year. Always refer to the abbreviations list printed at the front of the specific mark scheme you are using. This guide summarises the standard notations commonly found in IGCSE Mathematics and related subjects as of 2026.

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About the Developer

I am Chew, an education technology developer and academic consultant with 5+ years building educational websites. I developed the IGCSE Grade Calculator to bridge the gap between complex official PDF thresholds and student accessibility.

The mathematical models used in this calculator are verified against the Cambridge Assessment International Education (CAIE) guidelines for component weighting. This ensures that the “Total Weighted Mark” produced here matches the logic used by official examiners.