A-Level Economics · Teaching method · DRAFT
Chains of reasoning: the method behind A* economics essays
A chain of reasoning is a piece of economic analysis in which every logical step between the trigger and the outcome is written down explicitly — typically six or seven linked steps, each one caused by the step before it. I am George Chantry: Oxford PPE, a First, three Oxford prizes in economics and the best mark in my year in Game Theory, and I have taught A-Level Economics one-to-one for nine years and more than 7,000 hours.
Teaching students to write chains of reasoning is the single change that moves the most grades, because A-Level economics mark schemes reward the linking, not the conclusion. Most students stuck on a B are not short of knowledge. They are writing conclusions without the chain that earns them.
What a chain of reasoning actually is
Economics at A-Level is not a subject where you are paid for knowing the answer. You are paid for showing the route. The examiner has a mark scheme that awards credit step by step, and a step you did not write down is a step you do not get. That is the whole game, and almost nobody explains it to students plainly.
So a chain has a shape. It starts with a trigger — the policy, shock or event named in the question — then moves through a first economic mechanism, a second-order effect, a third-order effect, a knock-on effect, and finally an outcome that answers the question actually asked. Six or seven links is what a top band looks like on a 25-marker. Three reads fine and scores in the middle.
The unit inside each link is what I call point, cause, consequence. State the point. Explain the cause. Spell out the consequence. Then the consequence becomes the point of the next link, and you go again. Students find this liberating, because it turns "write a good analysis paragraph" — advice you cannot act on — into something mechanical you can check your own work against.
Why most students never write one
In my experience this is rarely laziness and almost never lack of intelligence. The material has been taught at a superficial level, where the details of the diagram and the chain relevant to the question were never taught. The student has the topic. They do not have the mechanism. So they assert the ending, because the ending is the bit they were told.
You can see it immediately in a student's writing: a single sentence that states the outcome, is not wrong, is worth a mark or two, and skips four steps that each carried credit. The examiner cannot award marks for reasoning that happened silently in the student's head.
One chain, worked in full
Here is the method on a real question — deliberately a short-tariff one rather than a 25-marker, because the point is the mechanics.
Exam-style question
“Assess the likely impact of a significant rise in the national minimum wage on a competitive labour market.”
The chain — seven explicit links
- Trigger. The government sets a minimum wage, Wmin, above the competitive equilibrium wage W1 — say the market wage was £10 an hour and the floor is set at £15.
- This means that the cost to a firm of employing each low-paid worker rises, and the firm cannot legally pay below the floor.
- Therefore a firm will only hire a worker whose marginal revenue product — the value of what that worker adds — is at least as high as £15. At £10, Tesco is happy to pay someone to stack shelves. At £15, Tesco says no, that worker no longer covers their own cost.
- As a result there is a contraction of demand for labour along the labour demand curve, from Q1 to Qd.
- Meanwhile the higher wage draws more people into this market through the income and substitution effects, so there is an extension of supply along the labour supply curve, from Q1 to Qs.
- Consequently quantity supplied now exceeds quantity demanded, and the distance Qs − Qd is an excess supply of labour — that is real wage unemployment, and you can read it straight off the diagram.
- So the workers who keep their jobs enjoy a higher standard of living, while those priced out lose their entire wage; inequality within the low-paid group therefore widens, even though the floor was meant to narrow it. The net impact depends on how far above equilibrium it is set, ceteris paribus.
Nothing is assumed; every "therefore" is doing real work. The real-world example — Tesco at £10 versus Tesco at £15 — is one short clause, there to make the mechanism concrete, not to pad. And the final link goes back to the words of the question, which is where a lot of otherwise good answers quietly stop.
What a B-grade answer writes
“A higher minimum wage causes unemployment because firms cannot afford to pay workers, which is bad for the economy.”
One assertion. Four links skipped — the cost rise, the MRP test, the contraction of demand, the extension of supply. No diagram, no link back to the question.
What the chain does
Seven links, each caused by the one before, each visible on the page.
Same knowledge, same student. The difference is entirely in what was written down — and it is worth several marks a paragraph, which is where whole grades come from.
The diagram is a chain too
The same discipline applies to diagrams, and this is the second place marks leak. Students draw a beautiful diagram and describe none of it. My rule is ACE: label the Axes, the Curves and the Equilibria — then, for every curve that shifts, do a point, cause, consequence. A diagram you have not narrated is decoration. A diagram you have narrated is another three or four links of analysis, already drawn for you.
KAA and evaluation: how many chains, and where
Edexcel splits its marks between knowledge, application and analysis on one side, and evaluation on the other — and evaluation is roughly 40% of the marks in essay questions. Chains of reasoning are the engine of the analysis marks and the gateway into the evaluation marks, because you cannot meaningfully evaluate an argument you never built. Students who go straight for evaluation, hoping it looks sophisticated, tend to score badly in both halves.
The balance I teach is deliberately narrow:
- 25-mark question: roughly four body paragraphs — argument one plus its evaluation, argument two plus its evaluation — then a judgement you actually commit to. Two evaluation points is enough. Each one should be a proper chain in its own right, not a sentence beginning "however".
- 10, 12 and 15-mark questions: one evaluation point is enough. The tariff does not reward breadth here; it rewards depth.
I teach this explicitly because most students believe the opposite — that three or four evaluation points look impressive. In practice four half-built evaluations score below two properly chained ones every time, and they cost you the minutes the analysis needed. Fewer arguments, developed further, is the whole trade.
Why this is worth learning beyond the exam
A chain of reasoning is not an exam trick. It is what an economist does. When the Treasury models a tax change or the Bank of England debates a rate rise, the argument is exactly this: which mechanism fires first, what does it do second, where does the effect land. Economic models are like the London Tube map — deliberately wrong in a hundred ways, useful in the one way that matters. Teaching a seventeen-year-old to write the steps down is teaching them to think in a way that outlasts the paper.
What this looks like in practice
Chains sit alongside the other two things I work on: question-to-topic mapping — working out what a question is really asking before you write — and diagnosing which of three categories a student's problem falls into: a knowledge gap, an application failure, or exam technique. Chains are usually the fastest lever, because the knowledge is already there and only the writing is missing.
The results I can point to: 82% of my Edexcel students achieved an A or A* in the 2024–25 exams — 18 A and A* grades across the two years, with an average improvement of around two grades, and A* the most common grade in both. I will not claim chains of reasoning did all of that alone. I will say it is the change I make first, in most students, because it is the one that shows up in a mark within a fortnight.
Try it on your own work
Take the last economics paragraph you wrote and count the links, not the sentences. Every time you can insert "but why?" between two of your sentences and have not already answered it, that is a missing link — and almost certainly a missing mark.
Then rewrite it with every step visible, using the connectors as scaffolding: this means that… therefore… as a result… consequently… so… If it feels laboured, you are doing it right. Examiners are not marking elegance. They are marking whether the reasoning is on the page.