On the ideal paragraph:
"A paragraph is a group of related sentences marked with beginning indention. While paragraphs have no specific length and no required number of sentences, they do conventionally have three characteristics: they arc unified, coherent, and adequately developed. That is, a paragraph presents a single thought, all its parts are clearly related to one another, and its point is sufficiently supported by details, examples, or explanations...In a well-written essay each paragraph supports the thesis sentence; each is directly linked to the thesis and is clearly related to other paragraphs in the essay…Body paragraphs develop the idea [presented in the thesis statement] in such a way as to make the essay interesting, informative, and convincing. Careful linking of paragraphs provides coherence to an essay, and if each paragraph in the body supports and develops the single main idea of the entire paper, the essay has unity."
Checklist for creating well-written paragraphs:
• Does the paragraph cover one main idea?
• Is this main idea clearly presented in the topic sentence, or at least very clear?
• Does each sentence in the paragraph support the point made in the topic sentence?
• Is the paragraph organized in a logical way?
• Do the sentences flow smoothly from one to another?
• Is the main idea sufficiently developed with examples, details, arguments, statistics and/or facts?
The Bad Paragraph
This paragraph, taken from the Little, Brown Handbook (LBH), shows what a paragraph that doesn't stay on topic well looks like. You can see that, while reading this, you end up wandering off track with the writer, which can be very frustrating.
People who suffer from "winter blues" may be suffering from S.A.D.-seasonal affective disorder. The classic symptoms include depression, mild anxiety, fatigue, withdrawal from social situations, overeating, a craving for sweets and carbohydrates, oversleeping, and a lack of energy, enthusiasm, and concentration. The craving for sweets, of course, is likely to lead to weight gain, which can be another problem. The symptoms of S.A.D. peak in the winter months, when the days are shorter and provide less sunshine. Winter days are colder, too, especially in the northern climates, and a person has to wear extra clothing. People who suffer from the disorder should try to get as much exposure to light as possible, especially outside, though bright indoor lighting and a sunny vacation can help too.
Where does the topic sentence go?
Usually, your topic sentence goes at the beginning of your paragraph, so your reader knows from the beginning where you're headed, as is the case in this example (also from LBH):
Most of the evening news programs consist of commercials, and most of the commercials are for products to treat the infirmities of old age. On "The CBS Evening News" last night I watched a commercial for an iron and vitamin tonic from 6:33 to 6:34. From 6:34 to 6:35 appeared a commercial for arthritis remedies. And that was followed by a thirty-second commercial for sleeping pills. At 6:40 appeared three more commercials: One showed an elderly man eating bran cereal; a second showed a hemorrhoid salve; a third showed a salve for aching muscles. A few minutes later another barrage of commercials came on, and two more series of them appeared still later. These ads dealt with such products as laxatives, life and health insurance, and pain relievers for head and stomach.
Of course, the topic sentence doesn't have to go at the beginning of the paragraph. Where are the topic sentences in these examples?
Write; don't phone. Use appropriate grammar and correct spelling. Type or word process, allowing yourself absolutely no errors. Use good quality paper that is clean and unwrinkled. Limit yourself to a single page if possible. Strike a tone that is positive, confident, and professional, but avoid being aggressive and self-aggrandizing. Tell why you are the suitable candidate, drawing on your background of experience and education. State your career objective. If you observe these features identified by personnel officers as critical to job application letters, you will be in a better position to have your application given serious consideration.
Measure your waist and hips at their widest points, and divide the waist measurement by the hip measurement. For example, if your waist is 32 inches and your hips 40 inches, your score is .8. If you are a man with a ratio higher than 1 or a woman with a ratio over .85, you may have to lose weight. This is a guideline for weight loss reported by the National Academy of Sciences. It is based on the idea that people who have excess fat around their middles are at a higher risk of heart attack than those who have their excess on their hips and thighs.
Occasionally you can fashion a paragraph where the main point is so clear that you don't need to explicitly state it in a topic sentence. (Be careful doing this unless you feel very confident about your paragraph writing skills!) Keep this rule of thumb in mind: if you can't explain the main point of your paragraph in one sentence, you probably need to revise that paragraph!
LBH uses the following paragraph as an example of a paragraph that can get away with not having an explicit topic sentence. Do you agree? Why or why not? What do you think the point of this paragraph is?
"We're going to play the 'come-up' game." says Leonard, holding aloft a picture. "Quid est [What's this]?" he asks. Hands fly up. "Caseus est [It's cheese]," pipes a nine-year-old named Cheryl. "Optime [Super]!" praises Leonard, and calls the proud pupil up front to play teacher with a new picture. After a relay of come-ups, Leonard leads a Latin sing-along of Rome Is Burning to the tune of Are You Sleeping, Brother John? climaxed by a fire dance with everyone shouting "Flammae, flammae, flammae!" -Time
LBH's advice on coherence in paragraphs:
"An effective paragraph is not only unified but also coherent. All its parts clearly relate to one another. You may have been told at times that your paragraphs are "choppy," that they don't "flow," or you may have noticed this feature in the writing of others. The reading is difficult, the meaning hard to follow, and each sentence seems to stand alone. There are ways to revise writing to make it smoother and more coherent: organizing the paragraph, using parallel structures, repeating or restating words and word groups, using pronouns, being consistent, and using transitional expressions. You will find these methods effective for gaining coherence within paragraphs and between paragraphs."
One way to keep your paragraphs coherent is to create sentences that have a similar structure. This technique is illustrate below, in another example paragraph from LBH:
After her first husband died of alcoholism, Carry Nation devoted herself to eliminating consumption of alcohol in the United States. Standing nearly six feet tall and weighing nearly two hundred pounds, she intimidated any drinker. Wielding rocks and hatchets, she destroyed dozens of saloons. In the course of a ten-year rampage, she terrorized thousands of Americans but inspired thousands more. Though her campaign ultimately failed, she lives on as a symbol of powerful conviction and unequaled zeal.
Another possibility for improving the coherence of your paragraphs is repetition:
The country cemetery today looks, I suspect, much as it did a hundred and fifty years ago, except that there are now more graves. A huge old yew tree dominates the grounds, shading the tombstones of the farmers and merchants. As the sprawling branches of the yew attract the visitor's eye, intense quiet attracts the ear. The intermittent buzzing of insects, whose sounds would go unnoticed in a busier atmosphere, accents the absence of the noises of human activity. Cattle graze silently and placidly beyond the barbed wire that fences the cemetery off from the surrounding grasslands. The scent of newly mown alfalfa from nearby fields permeates the cemetery, but the slightly bitter aroma of the yew dominates, cutting through the quiet and overriding, with the threat of death, the impression of shelter given by the tree's sprawling branches.
This article orignally appeared on

Paragraphs 9.6 of 10 on the basis of 2011 Review.