LibGuides: PrePALS Writing: Topic Sentences

LESSON: The Topic Sentence

Topic (or "Key") Sentences

In academic writing, readers expect each paragraph to have a sentence or two that captures its main point. They’re often called “topic sentences,” though many prefer to call them “key sentences.” There are at least two downsides of the phrase “topic sentence.” First, it makes it seem like the paramount job of that sentence is simply to announce the topic of the paragraph. Second, it makes it seem like the topic sentence must always be a single grammatical sentence. Calling it a “key sentence” reminds us that it expresses the central idea of the paragraph. And sometimes a question or a two-sentence construction functions as the key.

Key sentences in academic writing do two things. First, they establish the main point that the rest of the paragraph supports. Second, they situate each paragraph within the sequence of the argument, a task that requires transitioning from the prior paragraph.

Consider the following examples:

Version A:

Now we turn to the epidemiological evidence.

Version B:

The epidemiological evidence provides compelling support for the hypothesis emerging from etiological studies.

Both versions convey a topic; it is pretty easy to predict that the paragraph will be about epidemiological evidence, but only the second version establishes an argumentative point and puts it in context. The paragraph does not just describe the epidemiological evidence; it shows how epidemiology is telling the same story as etiology. Similarly, while Version A doesn't relate to anything in particular, Version B immediately suggests that the prior paragraph addresses the biological pathway (i.e., etiology) of a disease and that the new paragraph will bolster the emerging hypothesis with a different kind of evidence. As a reader, it's easy to keep track of how the paragraph about cells and chemicals relates to the paragraph about populations in different places.

A last thing to note about key sentences is that academic readers expect them to be at the beginning of the paragraph. This placement helps readers comprehend your argument. However, keep in mind that this isn’t a rule. Sometimes the paragraph’s purpose in a larger piece of writing necessitates that its topic sentence occur elsewhere.

Attribution:

English Composition I. Schoolcraft College.

License: Creative Commons Attribution Non-Commercial Share Alike .

Attributions:

"Supporting Paragraph Structure" Youtube, uploaded by The Learning Portal / Le Portail d’Apprentissage, 12 Sept. 2023, https://www.youtube.com/watch?v=sGmEJ2ppbeQ&t=101s

Permissions: YouTube CC-BY License

APPLICATION: Choose the Topic Sentence

Choose the topic sentence practice-IXL
Read and then click the topic sentence that best captures the main idea.

ASSESSMENT: Let's Practice!

The paragraph below lacks a topic sentence. Read the paragraph, and write an appropriate topic sentence for the paragraph. To check your understanding, we invite you to submit your writing to the Online Writing Center via this online Writing Center LINK. The link will bring you to a form. In the form, you may put "Pre-Pals" for the COURSE NAME, "None" for the INSTRUCTOR, and "Topic Sentence Assessment" for the "Assignment Title." You will receive feedback from the Writing Center about your topic sentence.

Create a topic sentence for the following paragraph:

Whether working at a local food bank or helping clean up a park, volunteers often form friendships and networks that last beyond the activity itself. In addition to social benefits, volunteering also helps individuals develop valuable life skills, such as communication, teamwork, and time management. These skills are useful not only in personal relationships but also in academic and professional settings. Finally, volunteering provides a deep sense of personal fulfillment, as it allows people to make a positive impact and feel more connected to their community. Through these benefits, volunteering becomes more than just a good deed—it becomes a meaningful and rewarding part of life.