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What Does a Topic Sentence Do?

Here are three typical explanations of what a topic sentence does:

It gives the main idea of the paragraph.
It states the topic of the paragraph.
It tells what the paragraph will be about.

According to those standards, here are some examples that seem to be okay as topic sentences.

When I was fourteen, I took my boat alone out in the ocean for the first time.
How I broke my leg playing football.
Last summer two friends and I spent two weeks surfing in Costa Rica.
My most recent home improvement project was installing a new garage door.
With four sisters and two brothers, I grew up in a large family.
My hobby is building and flying model airplanes.
For my high school graduation, my parents bought me the brand new Camry that I always wanted.
I work as a helper on a surveying crew.

A Topic Sentence Outline would list the thesis and all the topic sentences. Here is a Topic Sentence Outline that needs improvement.

Thesis: On our vacation to Italy was memorable because of the people, the countryside, and the food.

Topic Sentence 1: The people were different from the kind of people we were used to.

Topic Sentence 2: The countryside was beyond description.

Topic Sentence 3: Then there was the food.

Here is a more helpful way to think of what a topic sentence does.

Consider the last topic sentence in the outline: Then there was the food. What’s the paragraph about? The food.

What’s the point of the paragraph? We don’t know. From the thesis we guess the food was memorable, although we do not know if the memories are wonderful or dreadful. Similarly in the opening topic sentence of the outline, we can only guess in what way the people were different from the kind of people we were used to. Were they happy? sad? lively? solemn? lazy? industrious? rude? polite? arrogant? obsequious? (humble?)

If the details are appropriate we can learn the point, but we should not have to read the paragraph to know the point. We should know the point after we read the topic sentence.

The development must do more than simply “tell about” the topic of the paragraph. The development must illustrate, support, or defend the point.

None of the examples on page one makes a useful topic sentence because each merely gives the topic. Instead, a topic sentence must give a topic plus a point about the topic.

Here are some more helpful ways to understand what a topic sentence must do:

The topic sentence is the conclusion of the paragraph.
The topic sentence presents a claim to be proven or supported or defended.
A topic sentence keeps no secrets.
A topic sentence sounds more like an ending than an introduction.

Here are some useful topic sentences with the conclusion highlighted in blue. Adding the conclusion gives a specific point or purpose or focus to the topic. The Penguin Handbook uses focus to explain what a topic sentence does.

I was foolish when I took my boat alone out in the ocean for the first time.
Breaking my leg playing football caused me weeks of inconvenience.
Two weeks surfing in Costa Rica was a bargain vacation.
Installing a new garage door was a complicated project.
Growing up with four sisters and two brothers, I learned to plan ahead.
Building and flying model airplanes can be an expensive hobby.
My parents spoil me.
Working as a helper on a surveying crew can be hazardous.

Here are some common mistakes in adding conclusions to topic sentences:

Warning: Be sure your topic sentence is a complete sentence and not a fragmentary title: The Hazards of working on a surveying crew.

Warning: Be sure your topic sentence is an opinion to be supported and not a fact: Richard Nixon was the only president to resign from office.

Warning: Be sure your topic sentence opinion is not so narrow that only one fact (and not an entire paragraph) is needed to support it: My grandmother drives an old car.

Warning: Be sure your topic sentence is not too broad to be supported with 5 or 6 facts: Our nation’s educational system is in trouble.

Warning: some conclusions are too vague to offer a specific claim. Often the writer will ignore the vague opinion and simply tell about the topic. These sentences offer vague opinions that are just as unhelpful as topic sentences without any conclusion:

Elephants are interesting animals.
Van Gogh was a famous impressionist painter.
“ET” was a really good movie.
My grandfather is very old.
Many people are ignorant about the Florida Everglades. (This merely allows the writer to tell about the Everglades.
They should be narrowed down to a supportable conclusion.

Elephants have a complex social structure.
Van Gogh lived an unhappy life.
“ET” had many bothersome inconsistencies.
My grandfather is gravely ill.
The Florida Everglades has been endangered by highway construction, urban sprawl, and water mismanagement.

A Topic Sentence Outline would list the thesis and all the topic sentences:

Thesis: On our vacation to Italy we were immersed in the vitality of the people, the land, and the food.

Topic Sentence 1: Italians seem to savor every moment

Topic Sentence 2: Italy dazzled us with its beauty.
Topic Sentence 3: Every meal was delightful.

Notice that we now know the point of the paragraphs without having to read them.

Topic sentences and the thesis sentence are conclusions to be supported.

Last updated 9/18/06

This document is protected by copyright. It may be used and reproduced only for non-profit educational use.