Where IB Maths AA HL students lose marks — and exactly what to do about it
IB subject reports are released only to schools, so we have not read them and do not quote them. This page is built from the IB's free specimen markschemes, the IB's published syllabus hours, and public summaries by teachers and revision sites (each linked). Treat every point as lower confidence than our A Level and IGCSE pages, which use the boards' public reports.
Ordered by how often and how widely they were reported. The first 5 are free in full; Pro unlocks the fix and a worked example for every other one.
#1Accuracy: not exact, not 3 s.f., or rounded too early
What examiners saw: The public specimen markschemes state that answers should be exact or correct to 3 significant figures unless a question says otherwise. Tutor summaries of examiner feedback list rounding (and early rounding in multi-step questions) among the most common avoidable losses.
Fix: Keep full values in the GDC; round only the final answer, to 3 s.f. unless told otherwise. On Paper 1 (no calculator) leave answers exact.
Worked example (our own): A population grows as P = 1200e^(0.035t). Find t when P = 2000, then the population 5 years later.
Loses marks
e^(0.035t) = 5/3 ⇒ t ≈ 15
P(20) = 1200e^(0.7) = 2416.5, so 2420
Earns the marks
t = ln(5/3)/0.035 = 14.595… (keep this in the GDC)
Why: Rounding t to 15 before the second step changed the final answer. IB markschemes expect exact answers or 3 significant figures, from unrounded working.
#2"Show that": verifying the given answer instead of deriving it
What examiners saw: Summaries of examiner comments note that candidates substitute the given answer to check it, which is circular and earns no marks, or skip steps before the given line.
Fix: Start from the information given and write each step until you reach the printed result. "Verify" and "show that" are different commands.
Worked example (our own): Show that the equation x² + kx + 9 = 0 has equal roots when k = 6.
Loses marks
Substitute k = 6: x² + 6x + 9 = (x + 3)², which has equal roots. ✓ (verifying the given answer)
Earns the marks
Equal roots ⇒ discriminant = 0: k² − 4(1)(9) = 0
k² = 36 ⇒ k = ±6, so k = 6 is a value giving equal roots (as required)
Why: Working from the given answer (verification) is circular in a "show that". Start from the condition and derive the result.
#3Proof by induction: "let n = k" and no final sentence
What examiners saw: Tutor summaries report HL candidates losing marks for writing "let n = k" instead of "assume true for n = k", for not stating the base case properly, and for omitting the concluding sentence.
Fix: State the base case, assume P(k), show P(k + 1), then write the full concluding sentence.
Worked example (our own): Prove by induction that 1 + 3 + 5 + … + (2n − 1) = n² for all n ∈ ℤ⁺.
Loses marks
n = 1: 1 = 1 ✓. Let n = k: … so it is true.
Earns the marks
n = 1: LHS = 1, RHS = 1² = 1, so true for n = 1
Assume true for n = k: 1 + 3 + … + (2k − 1) = k²
Then 1 + 3 + … + (2k − 1) + (2k + 1) = k² + 2k + 1 = (k + 1)², so true for n = k + 1
Since true for n = 1, and true for n = k implies true for n = k + 1, it is true for all n ∈ ℤ⁺ by induction
Why: "Let n = k" is not an assumption. The final sentence (base case + inductive step ⇒ all n) carries its own mark.
What examiners saw: Secondary summaries of subject-report feedback single out trigonometry done with the GDC in the wrong mode, spoiling every later part of a question.
Fix: If the interval or the calculus uses π or radians, switch to radians. Check the mode at the start of every paper.
Worked example (our own): Solve 2sin x = 1.2 for 0 ≤ x ≤ π.
Loses marks
x = 36.9° or 143.1° (GDC in degrees)
Earns the marks
The interval is in radians, so the GDC must be in radians
sin x = 0.6 ⇒ x = 0.644 or π − 0.644 = 2.50 (3 s.f.)
Why: An interval written with π means radians. Check the mode before the first trig calculation of every paper.
What examiners saw: Revision-site guidance based on examiner feedback: method marks are given for writing what you asked the GDC to do. A bare wrong answer scores nothing.
Pro: the fix and a worked example (wrong vs right method) for this mistake are in Pro. See plans
What examiners saw: Candidates solve a "hence" part from scratch or on the GDC; tutor summaries list confusing "hence" with "hence or otherwise" among common misreadings.
Pro: the fix and a worked example (wrong vs right method) for this mistake are in Pro. See plans
#8Kinematics: displacement given when distance is asked
What examiners saw: Revision guidance written from markscheme requirements: total distance needs ∫|v| dt (or a clear split where v changes sign); integrating v alone gives displacement.
Pro: the fix and a worked example (wrong vs right method) for this mistake are in Pro. See plans
#9Probability: calculator syntax instead of notation, and "at least" misread
What examiners saw: Secondary guidance: examiners expect the distribution and probability statement, not GDC syntax, and "at least" is often translated wrongly.
Pro: the fix and a worked example (wrong vs right method) for this mistake are in Pro. See plans
The IB does not publish marks per topic and we have no question-level data for IB papers. Syllabus hours are a rough guide to how much of the exam each topic takes up. Total: 210 hours.
A one-page PDF of the ten most common mark-losing mistakes and how to avoid them. Print it and stick it inside your revision folder.
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Sources
Where this comes from
IB subject reports are released only to schools, so we have not read them and do not quote them. This page is built from the IB's free specimen markschemes, the IB's published syllabus hours, and public summaries by teachers and revision sites (each linked). Treat every point as lower confidence than our A Level and IGCSE pages, which use the boards' public reports.
IB subject reports (DP Mathematics AA and AI) — not used (restricted). The IB publishes a subject report after each session, but it is only available to schools. We did not use leaked copies. Everything on this page comes from public sources.
What are the most common mistakes in IB Maths AA HL?
The most repeated points are: Accuracy; "Show that"; Proof by induction. Each one on this page has the fix and, where free, a worked example showing the wrong and right method.
Which IB Maths AA HL topics come up most?
In the material we analysed, the biggest areas were Calculus (55 hours), Geometry and trigonometry (51 hours), Number and algebra (39 hours).
Is this a prediction of the May 2027 paper?
No one outside the exam board knows what will be on the next paper. The "focus" list is an informed prediction from how often topics appeared and how weakly they were answered; it is not a guarantee, so revise the whole specification.
Where does this information come from?
IB subject reports are released only to schools, so we have not read them and do not quote them. This page is built from the IB's free specimen markschemes, the IB's published syllabus hours, and public summaries by teachers and revision sites (each linked). Treat every point as lower confidence than our A Level and IGCSE pages, which use the boards' public reports.
IB Math Revision