The “topic sentence” is the sentence in which the main idea of the paragraph is stated.Readers generally look to the first few sentences in a paragraph to determine the subject and perspective of the paragraph. That’s why it’s often best to put the topic sentence at the very beginning of the paragraph. In some cases, however, it’s more effective to place another sentence before the topic sentence—for example, a sentence linking the current paragraph to the previous one, or one providing background information. It is unquestionably the most important sentence in the paragraph.
The topic sentence generally is composed of two parts: (a) the topic itself and (b) the controlling idea.
The topic is the subject of the paragraph. It is what the paragraph is all about. For example, in our sample paragraph ‘Smoking’ is the topic.
The Controlling Idea
The controlling idea is the point that you want to make about the topic. It guides the ideas provided throughout the paragraph and limits the scope of the paragraph. Here is an example of a topic sentence with a controlling idea:
Running provides many healthful benefits.
The topic of this topic sentence is running. The controlling idea is healthful benefits. That is, the reader knows from this sentence that the paragraph is generally about running. And the reader also knows that the point of the paragraph will be to enumerate the healthful benefits of running.
N.B: Before writing any essay or even a paragraph, it is important to think, first about the topic and then what you want to say about the topic. Most often, the topic is easy, but the question then turns to what you want to say about the topic which is the controlling idea.
A good topic sentence is specific and well focused, guiding the entire paragraph. A good topic sentence:
▲ Is specific. If the topic is too general (for example, I like camping.), the reader will not know what to expect in the paragraph.
▲ Is general enough to invite exploration of the topic. If the topic sentence is too specific (for example, Webster’s New World Dictionary has more than 40,000 words.), there will be nothing else to say on the subject.
▲ Is strong. Starting a topic sentence with there is/are (as in There are several ways to cook rice.) is a weak opener.
▲ Is not an announcement. A topic sentence should draw the reader into the paragraph. Announcements (like This paragraph will discuss how to build a bird house.) hold little attraction for readers.