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 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.
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.
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.
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:
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).
