Most students first encounter IB mark scheme codes as a confusing wall of letters — M1, A1, A1FT, R1 — scattered next to a final answer with no explanation. Once you understand the logic behind them, though, they become one of the most useful tools you have: they tell you exactly how marks are actually distributed, which is often very different from how a final answer alone would suggest.
The two main types of marks
| Code | Meaning | Awarded for |
|---|---|---|
| M (Method) | Method mark | Using a valid, appropriate approach — even if the arithmetic that follows is wrong |
| A (Accuracy) | Accuracy mark | A correct numerical result or expression, usually depending on a preceding M mark |
| R (Reasoning) | Reasoning mark | Valid justification, explanation, or interpretation — common in "explain why" or "show that" questions |
| AG | Answer given | No mark for the final answer itself (it's given in the question) — marks come from valid working leading to it |
| FT | Follow-through | A mark still awarded using a wrong earlier value, if the method from that point on is otherwise correct |
Why this matters more than most students realise
The single most important thing to understand is this: a completely wrong final answer does not mean zero marks. If you set up a correct method (M1) but make an arithmetic slip partway through, you can still pick up that M mark plus any follow-through (FT) marks for correctly continuing with your (now incorrect) numbers. This is why examiners repeatedly say "show your working" isn't just a formality — it's often worth more marks than the final answer itself.
Never leave a question blank just because you're not confident in the final answer. Write down the correct method, even incomplete — an M1 mark for a valid approach is still real credit, and it's credit you get zero of by leaving the space empty.
How follow-through (FT) actually works
Say a question has three parts, and part (a) asks you to find a value that part (b) then uses. If you make an error in part (a) but use your (incorrect) answer correctly and consistently in part (b), you can usually still earn the marks in part (b) — this is the "follow-through" principle. It exists specifically so that one early slip doesn't wipe out every mark in the rest of a multi-part question, which is especially relevant in longer, scaffolded questions like Paper 3.
Why "R1" questions catch people off guard
Reasoning marks are different from method and accuracy marks because there's often no calculation to show — the mark is for the quality and correctness of your written explanation. Students who are strong at calculation sometimes lose these marks simply because they didn't write anything down, assuming the answer "was obvious." If a question says "explain," "justify," or "show that," a numerical answer alone — even the correct one — typically won't earn the R mark on its own.
A quick way to self-mark more accurately
- Before checking the final answer, look at how many total marks the question is worth and how they're distributed (M vs A vs R) — this tells you where the actual credit lives.
- Check your method line by line against the mark scheme's method mark, even if your final number is wrong.
- If you made an early error, check whether your later work would have earned follow-through credit — don't just mark the whole question as "wrong."
- For "explain" or "show that" style parts, check whether your written reasoning (not just your final number) matches what's expected.
Practise with full mark schemes
Every generated question comes with a complete M1/A1/R1 breakdown, so you can self-mark accurately.
✦ Try it freeFrequently asked questions
Do all IB Math questions use M, A, and R marks?
Most questions use a mix of M and A marks; R marks appear specifically where reasoning or justification is required, which varies by question rather than appearing in every one.
What does "AG" mean if there's no mark attached to the final line?
AG ("answer given") means the final result is stated in the question itself — your job is to show valid working that arrives at it, and the marks come from that working, not from restating the given answer.