The one-sentence truth: A topic sentence is not a label for the paragraph. It is the paragraph’s first act of reasoning.
Weak topic sentences announce subjects: “Another factor is education.” Strong topic sentences make claims: “Education can reduce inequality where school quality is not strongly determined by household income, but its effect is limited when labour-market rewards remain highly unequal.” The second sentence tells the reader what the paragraph will prove, where the claim holds and what limitation matters.
The four jobs of a topic sentence
- Claim: say something arguable.
- Direction: show how the paragraph advances the thesis.
- Scope: define who, where or when the claim applies.
- Criterion: indicate why the claim matters.
Useful topic-sentence vocabulary
| Function | Useful language |
|---|---|
| Rank | more significant, principally, comparatively, secondary |
| Qualify | largely, particularly where, insofar as, contingent on |
| Contrast | by contrast, however, nevertheless, whereas |
| Evaluate | defensible, limited, consequential, proportionate |
| Cause | drives, enables, constrains, exacerbates, mitigates |
A topic sentence must be smaller than the thesis
Your thesis governs the whole essay. Each topic sentence should take one slice of that larger position. If the thesis argues that AI’s educational value depends on task design, teacher oversight and student knowledge, individual paragraphs can each examine one condition without restating the entire thesis.
Avoid paragraph labels
“Firstly, there are economic benefits” is organisational language, not analysis. Better: “The strongest economic case for automation lies in productivity gains where routine tasks can be standardised and verified.” The reader immediately sees both the claim and the condition.
Build hierarchy
If one paragraph contains your strongest reason, signal why. Words such as principal, decisive, comparatively significant and secondary help establish a ranking rather than a flat list of points.
Topic sentences and counterargument
A counterargument paragraph should also begin with a real claim: “The strongest objection to stricter regulation is not cost but the risk of granting authorities excessive discretion over legitimate expression.” That sentence tells the reader why this objection deserves attention.
From weak to strong
Weak: “Another reason why public transport is good is convenience.”
Stronger: “High-capacity public transport is most socially valuable where it provides a credible substitute for private driving, because that substitution allows cities to reduce congestion without merely restricting mobility.”
The topic-sentence test
- Can a reasonable reader disagree with it?
- Does it advance the thesis?
- Does it identify a mechanism, criterion or comparison?
- Is it narrow enough for one paragraph?
- Does the evidence that follows actually support it?
Seven-day drill
- Rewrite ten label-style openings as claims.
- Add scope to five topic sentences.
- Add a criterion to five.
- Write a ranked paragraph sequence.
- Write a counterargument topic sentence.
- Check whether evidence matches the claim.
- Draft a whole essay using topic sentences only.
Continue the JC2 GP vocabulary system
Return to the canonical General Paper Vocabulary Year 2 (JC2) and the broader Vocabulary for Junior College (JC1–JC2).
Final thought
A good topic sentence makes the paragraph feel necessary before the evidence even begins.