If you’re going to talk about topic sentences, you need to start by talking about paragraphs. You’ll recall that a paragraph is one unit or chunk of writing that’s meant to cover one main idea in full.
Usually, a paragraph is part of a larger piece of writing, and it is distinguished from other paragraphs by having either the first line indented or by having a blank line separating it from the paragraphs above or below.
Since a paragraph is meant to cover just one central idea, paragraphs are usually between three and seven sentences, which might be roughly 100 to 200 words or so.
However, a paragraph isn’t just any sentences thrown together. There’s a structure, which usually looks something like this:
In addition to simply beginning a paragraph, a topic sentence captures the main point or controlling idea of a paragraph.
A controlling idea is just the main idea around which the whole paragraph revolves; it’s the purpose of the paragraph. Every other sentence is designed to support and develop that main, controlling idea.
Read the following paragraph and consider the topic sentence.
Traveling to other countries is one way that people can become more tolerant. Exploring a new culture firsthand can help people expand their assumptions about the world. Meeting people and making friends in these different cultures helps travelers understand different people better. Thus, when they return home, they will be more likely to accept the diversity in their own lives. All of this causes an increase in tolerance.
Here it’s clear that “Traveling to other countries is one way that people can become more tolerant” is the topic sentence. See how it announces what the paragraph is going to be about? It’s almost like a title telling you what to expect from this paragraph.
For this reason, topic sentences are usually, though not always, the first sentence in a paragraph. That way, readers are introduced to the paragraph through this topic sentence.
Now that you know what a topic sentence is, it’s time to learn how to write a strong and effective one.
There are a few guidelines to keep in mind when writing a topic sentence:
If your topic sentence is too narrow, your readers will only know to expect one aspect of the paragraph. If it’s too broad, your readers won’t know what to expect from the paragraph.
Try to focus on the topic and what the supporting sentences will do. Then, summarize that as the topic sentence.
Here is an example paragraph with a topic sentence that’s too narrow:
Not wearing appropriate clothes at work can be dangerous. If clothing is too casual, such as blue jeans in an office, coworkers may feel that the employee doesn't respect their shared job. If clothing doesn't match the job's needs, such as close-toed shoes in an active work zone, the employee may be injured. Therefore, it is best to communicate clearly to employees what clothing to wear in order to facilitate a respectful and safe workplace.
See how the topic sentence doesn’t actually introduce the material that the paragraph covers? It’s not effectively providing a summary of what this whole paragraph is about, just of one of the points.
Now here’s a topic sentence that’s too broad:
Workplaces need to be comfortable for everyone. If clothing is too casual, such as blue jeans in an office, coworkers may feel that the employee doesn't respect their shared job. If clothing doesn't match the job's needs, such as close-toed shoes in an active work zone, the employee may be injured. Therefore, it is best to communicate clearly to employees what clothing to wear in order to facilitate a respectful and safe workplace.
Notice how big this idea is. Do you think all of the material this introduces could be sufficiently covered in a mere three to seven sentences? No way. And do you know specifically that this paragraph is going to be about dress codes? No.
A topic sentence that’s too broad will usually require several paragraphs to explain all of its material, and thus should be narrowed down to address just the main point of the single paragraph.
The third one is too broad. “More productive” in what way? The sentence doesn’t tell you. The second one is too narrow. Community is just one of the points in the paragraph.
The first one, however, introduces the paragraph effectively by announcing the main point and fully addressing both elements of the content of this paragraph.
Before your guests even arrive, you might give them an idea of what you intend to cook. This way, if you have guests who have food allergies or other restrictions, they will be able to prepare for their own unique needs. Then, once guests arrive, welcome them with an offer of appetizers and drinks. This way, no one will be hungry or thirsty while waiting for dinner to be served. These little tricks will assure the comfort of any guest at your dinner party.
Looking at the last sentence can give you a clue, as that concluding sentence is there to sum up the main idea of the paragraph. With that in mind, the completed paragraph with the topic sentence might look like this:
When you're throwing a dinner party, it's important that you pay attention to everyone's physical comfort. Before your guests even arrive, you might give them an idea of what you intend to cook. This way, if you have guests who have food allergies or other restrictions, they will be able to prepare for their own unique needs. Then, once guests arrive, welcome them with an offer of appetizers and drinks. This way, no one will be hungry or thirsty while waiting for dinner to be served. These little tricks will assure the comfort of any guest at your dinner party.
Sometimes, after you’ve written a topic sentence and then a full paragraph, you might realize that what you wrote in the paragraph has transformed in the process of writing and no longer matches that topic sentence.
Perhaps you realize that you had a more narrow focus as you wrote, or perhaps you changed your opinion in the process of writing. That isn’t a bad thing.
In fact, it’s great because writing is a process, not a product, and it should include rethinking, revising, and rewriting. However, it does mean that you will need to revise your topic sentence so that it remains aligned with the content of your paragraph.
The following is a revised version of the paragraph about dinner parties.
Before guests arrive, give them a menu. This way, if you have guests with food allergies or other restrictions, they will be able to prepare for their own unique needs. If you've invited vegetarians, they may wish to bring a suitable main course to add to the menu. Likewise, if you plan to cook a dish and a guest has an allergy to its ingredients, you will have time to alter the recipe. Thus sharing the menu can help assure the comfort of all your guests.
Obviously the content of the paragraph is a little different than the original topic sentence (“When you’re throwing a dinner party, it’s important that you pay attention to everyone’s physical comfort”) suggests.
Options 1 and 3 are a little too broad. Conversely, options 2 and 4 are too specific; they’re not covering everything. Number 5, however, explains that this paragraph will specifically cover the issue of sharing the menu with dinner guests in order to make sure that they feel comfortable at your party. So number 5 would be the best choice.
Source: This work is adapted from Sophia author Martina Shabram.