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Topic Sentences in Your Research Paper

When you compose a piece of writing, it's important to organize your ideas so readers understand your main point and sub-points. Creating a topic sentence for your introductory paragraph and supporting paragraphs is an essential part of non-fiction writing. Learning how to write effective topic sentences can help you present your main idea and supporting information clearly to your audience (How to Write, Indeed).

The topic sentence is typically at the beginning of the paragraph to outline the subject of the paragraph. Sometimes, a topic sentence comes after a transition from the previous paragraph. A topic sentence can be two to three sentences long (How to Write, MasterClass)

Topic sentences should contain your point of view or opinion to grab your reader's attention. Avoid stating obvious facts in topic sentences (How to Write, MasterClass).

A topic sentence is the opening sentence to a paragraph that gives the general idea (topic) of what the writing will be about. It needs to give broad enough information to allow for multiple subtopics and examples without being so general that it makes the purpose of the writing unclear.

Topic sentences help guide the reader by introducing the subject of the rest of the paragraph. They relate to the main idea of the entire piece of writing and present the specific topic that is the focus of a paragraph. Topic sentences provide structure to a paragraph and piece of writing as a whole.

  • Tea has long been studied and enjoyed for its beneficial properties.

  • Before leaving office, President Polk acquired territory in the western United States.

  • Humans can more easily reach Mars by using the moon as a launch base.

  • Many deep areas of the Pacific Ocean have never been studied by humans.


(How to Write, Indeed).

"How to Write a Topic Sentence.", 31 July 2023,


"How to Write a Topic Sentence." MasterClass, 28 Sep 2022,

As I have said several times, do not begin your sections with a statement of fact. From the beginning, I've said and posted that your paper should be more than just the regurgitation of facts. I've shown you the George Washington example many times. My four-sentence introduction to the section lays out its topic. I then proceed to relate the facts that led me to that conclusion. 

Whatever you write in your topic sentence(s), that's the ONLY thing that paragraph/ section should be about.

Don't begin with George Washington was born on February 22, 1732. (1) It's a fact, and (2) it limits what your early life section will be about.

Instead, at a minimum, write George Washington had an interesting childhood. That's an opinion and then you can write all about his childhood including basic facts and interesting details such as him becoming a slave owner at age 11 when his father died and not having a formal education, but being mostly self-taught.

What about endangered species?

Let's take a look at a few facts about the Snow Leopard

  • Their well-developed chests help them draw oxygen from the thin mountain air;

  • The length of their legs, size of their paws, and meter long tail gives them extra balance on rocky cliffs;

  • Their large nasal cavities allow them to warm the cold mountain air before breathing it into their lungs;

  • Their wide feet are like snow shoes;

  • They have a "dense, woolly underfur" that helps keep them warm.

After considering all of these facts, I reach this conclusion: Snow leopards are well adapted to their high altitude homes and that becomes my topic sentence.

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