Task 2 · Cross-cutting skill

Topic sentences — the skill, not the paragraph

This does one job: it opens a paragraph by naming the one claim that paragraph exists to support. The first sentence of every body paragraph, in both tasks. It is also the sentence that decides whether the paragraph will develop an idea or list several, which makes it worth more than its length suggests.

The long versionwhat it is, what it costs, where it stops

4 examplesworked, and the mistakes with their repair

Guided practice3 steps, you write, then you compare

3 exercisesevery wrong option explains itself

Start here · the long version

What topic sentences really asks you to do

A topic sentence names the single claim a paragraph will support, and it commits the rest of the paragraph to staying on it.

One idea, or the paragraph drifts

A topic sentence that names two ideas gives the paragraph permission to wander between them, and the paragraph almost always takes it. “Public transport is cheaper and better for the environment” looks efficient and produces a paragraph that half-argues two things — which reads as a list, because it is one. Naming one idea forces every following sentence to answer to it, and that constraint is the whole point of the sentence.

The second requirement is that the claim be arguable. “Many people use public transport” is a fact, and a paragraph cannot develop a fact: there is nothing to support, so the sentences that follow can only add more facts. “Public transport is underfunded relative to its usage” is contestable, and everything after it has a job.

The third is that it belong to the essay. A topic sentence has to advance the thesis, not merely introduce a subject that is nearby — a paragraph that opens with a true, arguable claim your position does not need is a paragraph the examiner cannot connect to the answer.

One claim

Two ideas in the opening sentence produce a paragraph that argues neither properly.

Arguable

If nobody could disagree, the paragraph has nothing to develop and can only add facts.

Connected to the thesis

It has to move your position forward, not merely be about the same topic.

First, not buried

A claim that arrives in sentence four leaves the reader three sentences without knowing what the paragraph is for.

What it costs you to skip this

A two-idea topic sentence costs on Coherence directly: the paragraph has no single controlling idea, which is exactly what the criterion describes. It costs again on development, because two half-argued ideas score below one properly extended — and the writer usually experiences the paragraph as richer, not thinner, which is why the error survives rereading.

Where it stops applying

A topic sentence is not a summary of the paragraph, and writing it as one produces an opening that gives away the reasoning before the reasoning happens. It also does not belong in the introduction or conclusion: those paragraphs have their own jobs, and a topic sentence in the introduction is usually a thesis with the reasons attached.

Examples · watch, then the mistakes

The skill working, and the two ways it fails

Worked example · The most compelling argument … is

The most compelling argument for restricting city-centre traffic is the measurable improvement in air quality.

Why it works: One claim, arguable, and marked as the strongest — so the paragraph beneath it knows it has to earn that description. Naming a second benefit here would have licensed the paragraph to drift.

Worked example · matters most for

Free entry matters most for the visitors least likely to come back a second time.

Why it works: Narrow enough that the paragraph can actually support it, and contestable enough that supporting it is worth doing. A reader can disagree, which is what makes the following sentences necessary.

Public transport is cheaper and better for the environment.

Two ideas, so the paragraph will argue each one halfway. It reads as efficiency and produces a list.

Repaired: Public transport is substantially cheaper per journey than private car use.

Many people in cities use public transport every day.

A fact, not a claim. Nothing follows from it, so the paragraph can only add more facts.

Repaired: Public transport is underfunded relative to the number of journeys it carries.

Now you try · with the scaffolding on

Build it one step at a time

Write a topic sentence that forces the paragraph to stay on one idea.

The material

Your thesis: cities should restrict private cars in the centre. You are writing Body 1 on the health case.

Step 1Write the two ideas you could open with

Air quality and noise are both health arguments. Write both — you are going to discard one.

Your version0 words · minimum 8

8 more words before you can compare. Writing it yourself first is the whole exercise.

Step 2Choose one, and make it arguable

Step 3Check it against the thesis

Exercises · production

Now judge it without the scaffolding

Every wrong option is wrong for its own reason, and it says so. Nothing here is scored automatically.

Which is the strongest topic sentence for a paragraph arguing that libraries deserve more funding?

Choose an option first

Your topic sentence names two benefits. What is the likely consequence?

Choose an option first

Where should the topic sentence go?

Choose an option first

Where it is practised

This skill lives in a stage of the essay too

Build Body 1

Where this skill is built into a paragraph, with the rest of the stage around it.

Thesis and position

It states the answer to the question and keeps that answer visible from the first paragraph to the last.

Explanation and development

It takes one claim and follows it, instead of stating four claims and following none.

Examples and evidence

It makes an abstract claim concrete, without pretending to a source you do not have.

Contrast and concession

It admits what is true in the opposing view and then explains why your position survives it.

Sentence types

It varies the shape of your sentences for a reason, instead of writing every sentence the same way.

Critical final review

It checks the four things that can still be fixed, in the order that finds the expensive problems first.