5.1 The Structure of a Paragraph


This section of Ch. 5 will cover the following:

  • topic sentences
  • supporting detail
  • transitions and conclusions
  • paragraph length

The basic building blocks of language are words. Words form sentences. Sentences combine to make paragraphs. And paragraphs can stand alone or be combined to become essays, research papers, reports, letters, and books.

This chapter covers the components of a paragraph, different types of paragraphs, and using paragraphs to build longer documents.

The Parts of a Paragraph

A paragraph is composed of a topic sentence, supporting information, and a concluding point or transition.

Topic Sentences

The main idea of the paragraph is stated in the topic sentence. A good topic sentence does the following:

  • introduces the rest of the paragraph
  • contains both a topic and an opinion
  • is clear and easy to follow
  • does not include supporting details
  • engages the reader

For example:

Development of the Alaska oil fields created many problems for already-endangered wildlife.

This sentence introduces the topic and the writer’s opinion. After reading this sentence, a reader might reasonably expect the writer to go on to provide supporting details and facts, such as what the problems are and how they were created. The sentence is clear and the word choice is interesting.

Here is another example:

Major league baseball has a history of cheating.

Again, the topic and opinion are clear, the details are saved for later, and the word choice is powerful.

Now look at this example:

I think that people should not take their pets to work, even for special occasions, because it is disruptive and someone might get bitten by a dog or a rabbit.

Even though the topic and opinion are evident, there are too many details (under what conditions, types of pets, different consequences). The phrase “special occasions” is vague. “I think” is usually unnecessary in academic writing; if you are writing the information, we know it is what you think.

Revised, that sentence might read like this:

People should not take their pets to work.

Much clearer, right?

Put the topic sentence at the beginning of the paragraph. In college and business writing, readers often lose patience if they are unable to quickly grasp what the writer is trying to say. Topic sentences make the writer’s basic point easy to locate and understand.

Exercise 1

Create a topic sentence for each of the subjects below. First, narrow the topic to something that could be discussed in a single paragraph.  For example, you might narrow the topic “animals” to “animals shelters” or “polar bears.” Then write a topic sentence about why people should adopt pets from shelters or how global warming is making life difficult for polar bears.)

  1. animals
  2. exercise
  3. social media
  4. movies

Write the four sentences in your notebook.  Be sure all the sentences meet the criteria listed above for a good topic sentence.

Supporting Ideas

The body of a paragraph contains supporting details to help explain, prove, or expand the topic sentence. For example, a paragraph on the topic of people continuing to work into their 70s might have a topic sentence like this:

Retirement is a moving target for many older Americans.

Supporting sentences could include a few of the following details:

  • Fact: Many families now rely on older relatives for financial support.
  • Reason: The life expectancy for an average American is continuing to increase.
  • Statistic: More than 20 percent of adults over age 65 are currently working or looking for work in the United States.
  • Quotation: Senator Ted Kennedy once said, “Stabilizing Social Security will help seniors enjoy a well-deserved retirement.”
  • Example: Last year, my grandpa took a job with Walmart.

A topic sentence guides the reader by signposting what the paragraph is about, so the rest of the paragraph should relate to the topic sentence. Can you spot the sentence in the following paragraph that does not relate to the topic sentence?

Health policy experts note that opposition to wearing a face mask during the COVID-19 pandemic is similar to opposition to the laws governing alcohol use. For example, some people believe drinking is an individual’s choice, not something the government should regulate. However, when an individual’s behavior impacts others–as when a drunk driver is involved in a fatal car accident–the dynamic changes. Seat belts are a good way to reduce the potential for physical injury in car accidents. Opposition to wearing a face mask during this pandemic is not simply an individual choice; it is a responsibility to others.

If you guessed the sentence that begins “Seat belts are” doesn’t belong, you are correct. It does not support the paragraph’s topic: opposition to regulations. If a point isn’t connected to the topic sentence, the writer should tie it in or take it out.

Exercise 2

Choose one of the topic sentences you developed for Exercise 1. In your notebook, write the sentence.

Underneath it, write three supporting sentences. At the end of each, identify whether the sentence is a fact, reason, statistic, quote, or example. Use this format:

Topic Sentence: ____________________________________________________________

Supporting sentence # 1 _______________________________________________________ (type)

Supporting sentence # 2 ______________________________________________________ (type)

Supporting sentence # 3 ______________________________________________________ (type)

Concluding Sentences


Don’t introduce new ideas in a conclusion.  It will just confuse the reader.

In a stand-alone paragraph, a strong conclusion draws together the ideas raised in the paragraph. A concluding sentence reminds readers of the main point without repeating the same words.

Concluding sentences can do any of the following:

  • summarize the key points in the paragraph
  • draw a conclusion based on the information in the paragraph
  • make a prediction, suggestion, or recommendation about the information

For example, in the paragraph above about wearing face masks, the concluding sentence summarizes the key point: responsibility to others.

Exercise 3

Using the paragraph outline you developed for Exercise 2, write a concluding sentence that summarizes your main idea without repeating the same words.

Then, write a second, different concluding sentence that either draws a conclusion or makes a prediction, suggestion, or recommendation.

Write both sentences in your notebook. Which one do you prefer? Why? Write the paragraph out, with its topic sentence, supporting details, and concluding sentence.


In a series of paragraphs, such as in the body of an essay, concluding sentences are often replaced by transitions. Transitions are words or phrases that help the reader move from one idea to the next, whether within a paragraph or between paragraphs. For example:

I am going to fix breakfast. Later, I will do the laundry.

“Later” transitions us from the first task to the second one. “Later” shows a sequence of events and establishes a connection between the tasks.


A transition can appear at the end of the paragraph or at the beginning of the next paragraph, but never in both places.

Look at this paragraph:

There are numerous advantages to owning a hybrid car. For example, they get up to 35 percent more miles to the gallon than a fuel-efficient, gas-powered vehicle. Also, they produce very few emissions during low speed city driving. Because they do not require gas, hybrid cars reduce dependency on fossil fuels, which helps lower prices at the pump. Given the low costs and environmental benefits of owning a hybrid car, it is likely that many people will buy hybrids in the future.

Each of the bold words is a transition. Transitions organize the writer’s ideas and keep the reader on track. They make the writing flow more smoothly and connect ideas.

Beginning writers tend to rely on ordinary transitions, such as “first” or “in conclusion.” There are more interesting ways to tell a reader what you want them to know. Here are some examples:

Purpose Transition Words and Phrases
to show a sequence of events eventually, finally, previously, next, then, later on
to show additional information also, in addition to, for example, for instance
to show consequences therefore, as a result, because, since
to show comparison or contrast however, but, nevertheless, although

These words have slightly different meanings so don’t just substitute one that sounds newer. Use your dictionary to be sure you are saying what you mean to say.

Exercise 4

Look at the paragraph you finished in Exercise 3. Underline transitions that help the reader move from one point to the next.

If you need better transitions, change them.

Then rewrite your final, polished paragraph in your notebook.

Paragraph Length

How long should a paragraph be? The answer is “long enough to explain your point.” A paragraph can be fairly short (two or three sentences) or, in a complex essay, a paragraph can be half a page. Most paragraphs contain three to six supporting sentences.

As long as the writer maintains close focus on the topic and does not ramble, a long paragraph is acceptable in college-level writing. But often, a long paragraph will not hold the reader’s interest. In such cases, divide the paragraph into two or more shorter paragraphs, adding a transitional word or phrase.

In an essay, a research paper, or a book, paragraphs separate ideas into logical, manageable chunks. Effective writers begin a new paragraph for each new idea they introduce.


  • Topic sentences express the main idea of the paragraph and the writer’s opinion.
  • In most academic essays, the topic sentence appears at the beginning of a paragraph.
  • Supporting sentences explain, prove, or enhance the topic sentence by offering facts, reasons, statistics, quotations, or examples.
  • Concluding sentences wrap-up the points made in the paragraph.
  • Transitional words and phrases show how ideas relate to one another and move the reader on to the next point.


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