Paragraphs, Topic Sentences, & Transitions

Paragraphs are the building blocks of technical documents, and topic sentences and transitions are the mortar that hold the blocks together. Paragraphs put the information you need to convey to your audience into manageable pieces. And topic sentences and transitions show the pattern of that information, which you determine given your audience and purpose. Information order may vary from one document to the next; the pattern just needs to be visible, so your audience knows what to expect, and what’s coming next.

Paragraphs

A paragraph is “a group of sentences or a single sentence that forms a unit.”^[1] A paragraph can be made up of just one sentence, if that one sentence offers a discrete idea. However, most paragraphs contain a few sentences that coherently support one idea. If there is a lot of information related to that one idea, you may need to break that information into a few paragraphs. Create a new paragraph when there is some shift in topic or subtopic, or some shift in the way a topic is being discussed.

Note that unless you’re writing an extended document for an audience of technical experts, and even in that situation, paragraphs in technical documents tend to be relatively short. Here are some suggestions about paragraphs:

In longer technical documents, on a page of single-spaced text, you might have at least three-four paragraphs. This is an average; it’s not a requirement. You determine paragraphs based on type and coherence of information. You just need to avoid a page with one or two lengthy paragraphs, as big blocks of text are difficult to read.
Within shorter paragraphs, four-five sentences is a widely accepted average.
Use short paragraphs for web pages and documents that will be posted online.

In summary, look at long walls of text and think about breaking them up into individual “bricks.”

Topic Sentences

A topic sentence usually occurs toward the beginning of a paragraph. It indicates the focus, purpose, and contents of that paragraph, and in some cases may also preview additional topic sentences that follow the paragraph (e.g., The first of three results is that….) Topic sentences are like signposts. Taken all together, they show the writer’s “route,” the idea structure of the document.

Often, when you draft a technical document, you don’t consciously think about indicating your idea structure. Instead, you focus on getting words onto the page, trying to explain your topic. So, the revision process is the time go to back and strengthen topic sentences that can help readers understand where they are going, what’s coming up next, where they’ve just been, and how what they are reading connects to the document as a whole.

Here are some different types of topic sentences.

Type	Definition	Example
keyword topic sentence	Contains a keyword that hints about the content and organization of the upcoming material. Use if your section (one or more paragraphs) discusses multiple similar things (for example, problems, solutions, causes, consequences, reasons, aspects, factors).	During Samhain there are a number of activities the Celts took part in that resemble some customs we observe on Halloween today.
overview topic sentence	Names all the subtopics in the upcoming material. Use if you want to specify all the subtopics you will address.	Most brains exhibit a visible distinction between gray matter and white matter.
thesis-statement topic sentence	Makes an assertion—an argument—that the rest of paragraph must support. Use if your section proves a point and includes multiple supporting statements.	Although Babbage’s machines were mechanical monsters, their basic architecture was astonishingly similar to a modern computer.
topic definition	Names the term being defined, identifies the class it belongs to, and describes its distinguishing characteristics. It must contain highly specific information. Use if your section introduces an unfamiliar term.	Stress is a measure of the internal reaction between elementary particles of a material in resisting separation, compacting, or sliding that tend to be induced by external forces.
topic reference	Mentions the general subject at hand. It does not forecast what will be said about the subject. Use to remind your reader about the general subject.	The surface of Mars is thought to be primarily composed of basalt, based upon the Martian meteorite collection and orbital observations.
no topic sentence	Sometimes, you may not need or want a topic sentence. If your materials contain a story that leads to a point, or are part of a popular science or popular technology writing project, a topic sentence up front may be inappropriate.

Transitions

Transitions are words and phrases that indicate how ideas are linked to one another. Together with topic sentences, transitions are the mortar holding the bricks together. You can also think of transitions as bridges from one idea or topic to the next. Like topic sentences, transitions help integrate your information into a unified whole. If you don’t make the document’s “flow” of ideas clear, a reader may not understand how the pieces of information relate or connect to each other. Transitions guide your reader from one idea (one paragraph, one section) to the next.

Transitions can show:

more of the same – and, as well as, too, in addition to, additionally, also
sequence – then, next, before, after, subsequently, following, during, until
similarity or difference – similarly, but, on the other hand, instead
causes – because, consequently, as a result, thus
additional explanation – for example, to illustrate, for instance
closure of one concept / start of another – as you can see, in summary / next, however