What the examiners said about IAL P4 (WMA14) — and exactly what to do about it
We read every Pearson Edexcel examiner report for WMA14 from June 2024 to June 2025, mapped each question to a topic, and turned the comments into a checklist of the mistakes that cost the most marks.
Summaries are in our own words with links to the originals. Predictions are informed guesses, not a guarantee.
Ranked for January 2027
What to focus on for January 2027
IAL units are sat in January, June and October. The October 2026 series is next; the ranking below is for your next sitting, whichever it is. Ranked by how often each area appeared, how many marks it carried and how weakly it was answered.
Informed prediction, not a guarantee: any topic on the specification can be examined.
1
Integration: substitution, parts and volumes
Two or three questions every series (14–23 marks).
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.
#1Differential equations: the constant added too late
What examiners saw: After separating variables, the constant of integration is missing or added after exponentiating (e^(x²) + c instead of Ae^(x²)), so the particular solution is wrong.
Fix: Add + c at the integration step, use the condition to find c, then rearrange.
Worked example (our own): Solve dy/dx = 2xy given y = 3 when x = 0.
Loses marks
ln y = x² ⇒ y = e^(x²) + c ⇒ c = 2 ⇒ y = e^(x²) + 2
Earns the marks
∫ (1/y) dy = ∫ 2x dx ⇒ ln|y| = x² + c
x = 0, y = 3 ⇒ c = ln 3
y = e^(x² + ln 3) = 3e^(x²)
Why: Add the constant when you integrate, before rearranging. e^(x² + c) is Ae^(x²), not e^(x²) + c.
#3Proof by contradiction: the assumption and conclusion
What examiners saw: The assumption is not written formally (or is not the exact negation, with the domain missing), and the contradiction is not stated.
Fix: Begin "Assume, for contradiction, that …" (including any domain), reach a contradiction, state it and conclude.
Worked example (our own): Prove by contradiction that there is no largest even number.
Loses marks
Assume there is an even number. Then n + 2 is even. So there is no largest.
Earns the marks
Assume, for contradiction, that there is a largest even number, N.
N + 2 is even (N = 2k ⇒ N + 2 = 2(k + 1)) and N + 2 > N.
This contradicts N being the largest even number.
So there is no largest even number.
Why: The assumption must be the exact negation of the statement, and the proof must end by naming the contradiction and the conclusion.
#4Connected rates of change: values not substituted, reasons missing
What examiners saw: dV/dr is found but not evaluated at the given radius; the answer is left in terms of r; the reason a rate is constant/decreasing is not given.
Fix: Write the chain rule linking the rates, substitute the given value, and give units.
Worked example (our own): A sphere's volume increases at 20 cm³ s⁻¹. Find the rate of increase of the radius when r = 5 cm.
Loses marks
dr/dt = 20 × 4πr² = 6283
Earns the marks
V = (4/3)πr³ ⇒ dV/dr = 4πr² = 100π when r = 5
dr/dt = (dV/dt) ÷ (dV/dr) = 20 / (100π)
= 0.0637 cm s⁻¹ (3 s.f.)
Why: Write the chain rule with units: dV/dt = dV/dr × dr/dt. Substitute the given r before the final answer.
#6Vector lines: "r =" missing, λ confused with coordinates
What examiners saw: Equations written as "l = …", parameter values quoted as the answer instead of the point, and the harder later parts not started without a diagram.
Pro: the fix and a worked example (wrong vs right method) for this mistake are in Pro. See plans
How often each topic appeared, and for how many marks
Every question in the papers we read, matched to a topic. Numbers are marks (from the published mark schemes; a question that tests two topics has its marks split). Columns marked * count questions (q) because the marks could not be verified from the mark scheme. Hover or tap a cell to see the questions.
Confidence: high for the series shown — every question was read and mapped by hand. "Series" = how many of the 4 series examined the topic.
Paper by paper
Every paper we analysed, question by question
Topics are ours (matched from each report's question-by-question comments). We don't reproduce the questions: open the official paper from our past-paper page.
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
We read the examiner report for every series from June 2024 to June 2025 in full and matched each question to a topic; marks come from the published mark schemes where the per-question totals could be checked against the paper total.
What do examiners say students get wrong in IAL P4 (WMA14)?
The most repeated points are: Differential equations; Binomial (any index); Proof by contradiction. Each one on this page has the fix and, where free, a worked example showing the wrong and right method.
Which IAL P4 (WMA14) topics come up most?
In the material we analysed, the biggest areas were Integration: substitution, parts, volumes, partial fractions, Parametric equations, Implicit differentiation and rates of change.
Is this a prediction of the January 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?
We read 4 Pearson Edexcel examiner reports (June 2024, October 2024, January 2025, June 2025) in full, summarised them in our own words and linked each point to the original.
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