Examples of Topic Sentences That Make the Purpose Clear

Updated July 6, 2022
Cat icon with Topic Sentence Example
    Cat icon with Topic Sentence Example
    Cat: VikiVector / iStock / Getty Images Plus / Background: Tolchik / iStock / Getty Images Plus
    Used under Getty Images license

What is a topic sentence? A topic sentence is the most important sentence in a paragraph. Sometimes referred to as a focus sentence, the topic sentence helps organize the paragraph by summarizing the information in the paragraph. In formal writing, the topic sentence is usually the first sentence in a paragraph (although it doesn't have to be). Keep reading for the two main parts of a topic sentence as well as topic sentence examples in different subjects.

Topic Sentences and Controlling Ideas

Topic sentences introduce a paragraph and connect to an essay's thesis statement, which is the topic sentence of your entire essay. Every topic sentence has two parts: a topic (what the paragraph is about) and a controlling idea (the direction the paragraph will take). Take a look at these topic sentence examples in which the topic is bold and the controlling idea is in italics.

  • Cats are very good pets for several reasons.
  • Our school's dress code policy has many negative consequences for girls.
  • The world population is strongly impacted by a lack of access to water.

The topic tells your audience what the paragraph will be about and connects to the thesis. The controlling idea tells them how you will explain it in this particular paragraph.


Topic Sentence Examples

Now that you know the main parts of a topic sentence, take a look at how they look in different subjects. Note that each example includes both a topic and a controlling idea.

  • Topic Sentence: There are many reasons why pollution in ABC Town is the worst in the world.
  • The topic is "pollution in ABC Town is the worst in the world" and the controlling idea is "many reasons."
  • Topic Sentence: To be an effective CEO requires certain characteristics.
  • The topic is "To be an effective CEO" and the controlling idea is "certain characteristics."
  • Topic Sentence: There are many possible contributing factors to global warming.
  • The topic is "global warming" and the controlling idea is "contributing factors."
  • Topic Sentence: Fortune hunters encounter many difficulties when exploring a shipwreck.
  • The topic is "exploring a shipwreck" and the controlling idea is "many difficulties."
  • Topic Sentence: Dogs make wonderful pets because they help you to live longer.
  • The topic is "dogs make wonderful pets" and the controlling idea is "because they help you to live longer."
  • Topic Sentence: Crime in poverty-stricken areas occurs as a result of systemic discrimination.
  • The topic is "crime in poverty-stricken areas" and the controlling idea is "systemic discrimination."

Examples of Topic Sentences as Transitions

Skillful writers use topic sentences to both introduce their paragraph and to transition from the previous paragraph. Topic sentences as transitions help the essay feel smoother and more cohesive to the reader.

Examples of topic sentences as transitions include:

  • Another way to reduce teen pregnancy rates is improved education.
  • In addition to needing the correct tools, cooking requires a number of different skills.
  • While purchasing real estate can be a good investment, it is important to be ready before buying a house.
  • Likewise, graduating from high school is important for many different reasons.
  • Even though having a baby can be a joyful event, having a first child is difficult because of the significant adjustments in your life.
  • Because there are so many options out there, remodeling a kitchen requires research and a good eye.

Supporting Your Topic Sentence

Coming up with a strong topic sentence is one thing, but how do you support it? Using your topic sentence as a frame, you can then fill in the reasons or evidence you have outlined in your controlling idea. For example, a paragraph that supports a topic sentence might look like this:

Cats are very good pets for several reasons. They are naturally good caregivers because they take care of their kittens, so they want to take care of their owners as well. Cats are quite clean, and if you train them to use a litter box, they require almost no cleanup in their areas. Finally, cats are independent, so you don't need to worry about them being lonely when you're at school all day. They really are the ideal pet for almost any owner.

Notice how the writer provided three reasons to back up the phrase "several reasons" in the controlling idea. All three reasons related to the topic "cats are very good pets." Also, the last sentence in the paragraph connects directly back to the topic sentence (though you can also make this sentence a transition sentence into your next paragraph).


Staying on Topic

Remember that topic sentences set the tone for the paragraph and should relate back to the thesis or the main idea of the paper. A carefully thought-out topic sentence helps you, the author, to stay focused. It also gives readers the tools they need to clearly understand what you have to say. If you're ready to get started on your next writing assignment, learn how to create a five-paragraph essay outline that is sure to keep your writing organized.