IB Economics SLTopic 5 — Assessment and Exam SkillsPaper 1Exam skill~9 min read
Structuring a Paper 1 Essay
The two halves of a Paper 1 question are built differently and marked differently. Part (a) is a clean explanation with no judgement in it. Part (b) is an argument that has to name real examples and end with a decision. Writing them the same way is the quickest route to an average mark on both.
📘 What you need to know
Part (a), 10 marks: mainly knowledge and application. Evaluation is not required.
Real-world examples are not required in part (a), so do not spend time hunting for one.
Part (a) wants accurate definitions where relevant, clear chains of reasoning, a correct diagram, and focus on the variable named in the question.
Part (b), 15 marks: evaluation leads, held up by knowledge, application and diagram skills.
Real-world examples are required in part (b), and they must be specific: a named policy, country, market or organisation.
An example must support the analysis, not replace it. A story with no theory attached earns very little.
The top band needs a justified, context-aware conclusion — a decision with a reason, not a summary.
The two shapes, side by side
Before writing anything, picture the shape of each half. Part (a) is a straight line from definition to conclusion of the theory. Part (b) is a loop: theory, one side, the other side, then back to the question with a verdict.
Both halves share the same theory. What differs is what you are asked to do with it once it is on the page.
Part (a): the 10-mark explanation
This half is a demonstration that you understand a mechanism. Define the term the question uses, set up the model, draw and label the diagram, then walk through the steps in order until you reach the variable the question named. Nothing else belongs here.
Only demand moves here. Supply is unchanged, and quantity supplied expands along the existing supply curve as price rises.
WORKED EXAMPLE
Explain how an increase in consumer income affects the equilibrium price and quantity in the market for a normal good. [10]
Paragraph 1: define and set up
A normal good is one where demand rises as income rises. Market equilibrium is the price at which quantity demanded equals quantity supplied.
Paragraph 2: the diagram
Draw D1, S and the equilibrium at P1, Q1. Shift demand right to D2. Mark P2 and Q2.
Paragraph 3: the chain, referring to the diagram
Higher income raises the ability and willingness to buy at every price, so demand shifts right from D1 to D2. At P1 there is now excess demand, so price is bid up. As price rises, quantity supplied expands along S until the market clears at P2 and Q2.
Paragraph 4: land on the named variables
Equilibrium price rises from P1 to P2 and equilibrium quantity rises from Q1 to Q2.
Define, diagram, chain, landNo “however”, no example, no verdict. Ten marks of clean explanation is all that is wanted.
If you catch yourself writing “on the other hand” in part (a), stop. That sentence belongs 30 minutes later, in part (b), where it is actually worth marks.
Part (b): the 15-mark argument
Here evaluation leads. You still need the theory and usually a diagram, but they exist to support an argument that ends in a judgement. The examiner is looking for a clear focus on the command term, theory that is woven in rather than dumped, at least one specific real-world example, both sides considered, and a conclusion that is justified and fits the context.
🧩 A paragraph plan for 15 marks
Set-up: define the key terms and say what the policy or change actually does.
Analysis: the theory with a diagram, explained as a chain. This is the base everything else stands on.
The case for: one strong point, developed, with a real example attached to it.
The case against: costs, opportunity cost, who loses, or what the effect depends on.
Judgement: which argument is stronger, in what conditions, and why. Name the reason.
What a usable real-world example looks like
specific (a named country, policy, market or firm) + accurate + tied to the theory in the same paragraph
WORKED EXAMPLE
Turn a weak real-world example into one that earns marks.
The weak version
“Many countries have used rent controls and they did not work very well.”
Why it scores little
No country, no time, no policy detail, and no link to the theory in the paragraph.
The version that works
“Cities that cap rents below the market level, such as long-running schemes in parts of Europe and North America, have reported falling numbers of units offered for rent. That is the shortage in the diagram appearing in practice: at the capped price, quantity supplied is below quantity demanded.”
Named, accurate, tied to the theoryThe example does not replace the analysis. It is evidence that the analysis describes something real.
WORKED EXAMPLE
Using real-world examples, evaluate the impact of imposing a maximum price on the rental housing market. [15]
1 Set-up
A maximum price is a legal ceiling set below the market equilibrium. Its aim is to make housing affordable for lower-income households.
2 Analysis with a diagram
At the ceiling, quantity demanded exceeds quantity supplied, so a shortage appears. Landlords supply fewer units at the lower price; more tenants want them.
3 The case for
Tenants who keep a controlled flat pay less, so their real income rises. Named example of a city scheme, plus what happened to rents there.
4 The case against
Shortages, queues and informal payments; landlords converting property to other uses; the quality of housing falling because there is no competition for tenants.
5 Judgement with a reason
“A maximum price protects existing tenants in the short run, but because supply of housing is inelastic in the short run and more elastic over time, the shortage grows. Unless it is paired with building more housing, it treats the symptom rather than the cause.”
Command term met, both sides, example, verdictThe conclusion earns its marks because it says when the policy works and why it stops working.
💡 Exam tip
Plan part (b) in five bullet points before writing. Two minutes of planning saves a paragraph of drifting.
Put your example inside the argument, in the same paragraph as the theory it supports, not in a separate story at the end.
Use the command term’s own word in your conclusion. If it says evaluate, evaluate.
Prepare three flexible examples before the exam: a tax, a subsidy or grant, and a price control. They stretch across many questions.
Keep the diagram in part (b) short. One diagram, explained in three lines, then get to the argument.
Write the judgement even if you are running out of time. Two honest sentences of judgement beat another paragraph of analysis.
⚠️ Common mix-up
Evaluating in part (a). There are no marks for it there, and it costs part (b) time.
Hunting for an example in part (a). Real-world examples are not required for the 10-mark half.
Vague examples. “Some countries” and “a few years ago” are not specific and cannot be checked.
An example with no theory attached. It becomes a news story rather than economics.
Confusing a shift with a movement along a curve. Income changes demand; price changes quantity demanded.
A conclusion that restates both sides. Balance is not the same as sitting on the fence.
Writing two part (a) answers, one for each half, and wondering why the second one scored lower.
Up next: Structuring the Paper 2 Response — the other 15-mark essay, which looks similar on the page but is marked on completely different things.
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