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IB Economics Paper 1: 10 and 15 Mark Structure

How to structure IB Economics Paper 1 answers: what the 10-mark part needs, what the 15-mark part needs, and where students lose marks.

IB EconomicsSL & HLFree revision notes
Contents: 7 sections

What Paper 1 asks of you

Paper 1 is the extended response paper. It is divided into Section A (microeconomics) and Section B (macroeconomics), and you answer one question in total, from either section, not one from each.

Every question comes in two parts:

The two parts reward completely different things. Most lost marks on this paper come from writing part (b) in the style of part (a), more theory, more diagrams, no judgement.

Part (a): the 10-mark explanation

Part (a) is not an essay. It is a controlled explanation with four jobs, and it is easiest to earn full marks by doing them in a fixed order.

1. Define the terms in the question. Every key term, briefly and precisely. If the question says "explain how a subsidy affects a market", define subsidy. Definitions are the cheapest marks on the paper and the most commonly skipped.

2, draw and fully label a diagram. A diagram earns marks only if it is labelled: both axes named, every curve labelled, the initial and new equilibrium marked, and the direction of any shift shown with an arrow. An unlabelled axis loses the mark even when the shape is right.

3, explain the mechanism as a chain. This is where the marks concentrate. Do not state the outcome, walk from cause to effect, one link at a time:

A subsidy lowers producers' costs → supply shifts right from S1 to S2 → at the original price there is now excess supply → price falls from P1 to P2 and quantity traded rises from Q1 to Q2.

Each arrow is a step an examiner can credit. Writing "a subsidy increases supply so price falls" compresses four creditable steps into one.

4. Give a real-world example. Name a country, market, firm or policy and say something specific about it. "For example, fuel subsidies in Indonesia" is worth more than "for example, some governments subsidise goods."

Part (b): the 15-mark evaluation

Part (b) is marked on whether you judge, not on how much you know. The structure below is deliberately front-loaded, so if you run out of time the examiner has already seen your analysis.

1. A one-sentence definition and a statement of the position you will argue. Do not write a long introduction. Say what the answer depends on.

2. Analysis, build two developed chains. One supporting, one qualifying. Each chain gets a diagram if the economics warrants one, and each is written as cause → mechanism → consequence, exactly as in part (a).

3. Application, anchor it in the real world. A named country, policy, industry or episode, with a specific detail. Vague gestures at "many economies" earn nothing.

4. Evaluation; this is what separates the bands. Evaluation is not a list of disadvantages. It is reasoning about conditions. Useful lines:

5. A conditional judgement. Not "in conclusion; it has advantages and disadvantages." A judgement states when the answer holds:

A subsidy is most likely to raise welfare where the positive externality is large and demand is relatively elastic, so the output gain is significant. Where demand is inelastic and the government is financing it by cutting other spending, the opportunity cost may exceed the external benefit.

What moves an answer up the bands

Examiners are looking for four things, and an answer is capped by whichever is weakest:

DimensionWhat a strong answer shows
TerminologyKey terms defined accurately and then used correctly throughout.
Theory and diagramsCorrect, fully labelled, and explicitly referred to in the prose.
ApplicationSpecific, named real-world material: not generic hypotheticals.
Evaluation (part b only)Reasoning about conditions, ending in a judgement that follows from the analysis.

A diagram that is drawn but never mentioned in the writing does almost no work. Refer to it directly: "as the diagram shows, the shift from S1 to S2…".

Common ways students lose marks

How to plan under time pressure

Spend the first few minutes deciding which question you can support with a real-world example, not which topic you like most. Application is where under-prepared answers collapse.

Then sketch, in the margin: the diagram for (a), and for (b) your two chains plus the condition your judgement will turn on. Three lines of plan prevents the most expensive mistake on this paper, which is realising halfway through part (b) that you have no evaluation to offer.

Part (b) carries half as many marks again as part (a). Divide your time accordingly, most students do the opposite.

Practise this

The fastest way to improve on Paper 1 is to plan many answers rather than write a few. Build the definition, the chain, the example and the judgement for a question. Check it, then move on.

The Answer Builder in the portal does exactly this: it walks you through the four steps for a 15-mark question and coaches each one, so you practise the reasoning before writing under timed conditions.

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