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Reading Comprehension: GED Test Prep (page 2)

By LearningExpress Editors
LearningExpress, LLC
Updated on Mar 9, 2011

Finding the Main Idea in Nonfiction

Most nonfiction texts follow a very basic pattern of general ideaspecific support. That is, the writer will state the main idea he or she wants to convey about the topic and then provide support for that idea, usually in the form of specific facts and details. This format can be diagrammed as follows:

Finding the Main Idea in Nonfiction

In the following paragraph, for example, notice how the first sentence states a main idea (makes a general claim about surveillance cameras). The rest of the paragraph provides specific facts and details to show why this statement is true:

Surveillance cameras can provide two immensely important services. One, they can help us find those who commit crimes, including thieves, kidnappers, vandals, and even murderers. Two, they can serve as a powerful deterrent to crime. A thief who plans to steal a car may think twice if he knows he will be caught on video. A woman who hopes to kidnap a child may abandon her plans if she knows she will be captured on film.

This main idea → support structure works on two levels: for the text as a whole and for each individual section or paragraph within the text.

Distinguishing Main Ideas from Supporting Ideas

If you're not sure whether something is a main idea or a supporting idea, ask yourself the following question: Is the sentence making a general statement, or is it providing specific information? In the following paragraph, for example, most of the sentences except one are too specific to be the main idea of the paragraph. Only one sentence—the first—is general enough to serve as an "umbrella" or "net" for the whole paragraph.

Many people are afraid of snakes, but most snakes aren't as dangerous as people think they are. There are more than 2,500 different species of snakes around the world. Only a small percentage of those species are poisonous, and only a few species have venom strong enough to kill a human being. Furthermore, snakes bite only 1,000–2,000 people in the United States each year, and only ten of those bites (that's less than 1%) result in death. Statistically, many other animals are far more dangerous than snakes. In fact, in this country, more people die from dog bites each year than from snake bites.

Notice how the first sentence makes a general claim about snakes (that they "aren't as dangerous as people think they are"). Then the rest of the sentences in the paragraph provide details and specific facts that support the main idea.

Writers often provide clues that can help you distinguish between main ideas and their support. Here are some of the most common words and phrases used to introduce specific examples:

These signal words usually mean that a supporting fact or idea will follow. If you are having trouble finding the main idea of a paragraph, try eliminating sentences that begin with these phrases. (Notice that one of the sentences in the snake paragraph begins with one of these transitional words.)

Topic Sentences

In nonfiction texts, the main idea is supported by ideas expressed in paragraphs. Each of these paragraphs also has its own main idea. In fact, that's the definition of a paragraph: a group of sentences about the same idea. The sentence that expresses the main idea of a paragraph is called a topic sentence. The first sentence in both the surveillance camera and snake paragraphs state their main ideas. Those sentences are therefore the topic sentences for those paragraphs.

Topic sentences are often located at the beginning of paragraphs, but not always. Sometimes writers begin with specific supporting ideas and lead up to the main idea. In this case, the topic sentence would probably be at the end of the paragraph. Notice how we can rewrite the snake paragraph to put the topic sentence at the end of the passage:

There are more than 2,500 different species of snakes around the world. Only a small percentage of those species are poisonous, and only a few species have venom strong enough to kill a human being. Snakes bite only 1,000–2,000 people in the United States each year, and only ten of those bites (that's less than 1%) result in death. Statistically, many other animals are far more dangerous than snakes. In fact, in this country, more people die from dog bites each year than from snake bites. Clearly, snakes aren't as dangerous as people think they are.

Sometimes the topic sentence is not found at the beginning or end of a paragraph but rather somewhere in the middle. Other times, there isn't a clear topic sentence at all. But that doesn't mean the paragraph doesn't have a main idea. It's there, but the author has chosen not to express it in a clear topic sentence. In that case, you will have to look carefully at the paragraph for clues about the main idea.

Finding an Implied Main Idea

When the main idea is implied, there is no topic sentence, so finding the main idea requires some good detective work. If you look carefully at what is said and at the structure, word choice, style, and tone of the passage, you can figure out the main idea. (These terms will be discussed in more detail later in the chapter.)

For example, take a look at the following paragraph:

This summer I read The Windows of Time. Though it's over 100 pages long, I read it in one afternoon. I couldn't wait to see what happened to Evelyn, the main character. But by the time I got to the end, I wondered if I should have spent my afternoon doing something else. The ending was so awful that I completely forgot I'd enjoyed most of the book.

There's no topic sentence here, but you should still be able to find the main idea. Look carefully at what the writer says and how she says it. What is she suggesting?

  1. The Windows of Time is a terrific novel.
  2. The Windows of Time is disappointing.
  3. The Windows of Time is full of suspense.
  4. The Windows of Time is a lousy novel.

The correct answer is choice b, the novel is disappointing. How can you tell that this is the main idea? First, we can eliminate choice c, because it's too specific to be a main idea. It deals only with one specific aspect of the novel (its suspense).

Choices a, b, and d, on the other and, all express a larger idea—a general assertion about the quality of the novel. But only one of these statements can actually serve as a "net" for the whole paragraph. Notice that while the first few sentences praise the novel, the last two criticize it. (The word "but" at the beginning of the third sentence signals that the positive review is going to turn negative.) Clearly, this is a mixed review. Therefore, the best answer is b. Choice a is too positive and doesn't account for the "awful" ending. Choice d, on the other hand, is too negative and doesn't account for the suspense and interest in the main character. But choice b allows for both positive and negative—when a good thing turns bad, one often feels disappointed.

Here's another example. In this passage, word choice is more important, so read carefully.

Fortunately, none of Toby's friends had ever seen the apartment where Toby lived with his mother and sister. Sandwiched between two burnt-out buildings, his two-story apartment building was by far the ugliest one on the block. It was a real eyesore: peeling orange paint (orange!), broken windows, crooked steps, crooked everything. He could just imagine what his friends would say if they ever saw this poor excuse for a building.

Which of the following expresses the main idea of this paragraph?

  1. Toby wishes he could move to a nicer building.
  2. Toby wishes his dad still lived with them.
  3. Toby worries about what his friends would think of where he lives.
  4. Toby is sad because he doesn't have any friends.

From the description, we can safely assume that Toby doesn't like his apartment building and wishes he could move to a nicer building (choice a). But that idea isn't general enough to cover the whole paragraph, because it doesn't say anything about his friends. Choice d doesn't say anything about his building, so it's not broad enough either. Besides, the first sentence states that Toby has friends. We know that Toby lives only with his mother and little sister, so we might assume that he wishes his dad still lived with them (choice b). But there's nothing in the paragraph to support that assumption and this idea doesn't include the two main topics of the paragraph—Toby's building and Toby's friends.

What the paragraph adds up to is that Toby is embarrassed about his building, and he's glad none of his friends have seen it (choice c). This is the main idea. The paragraph opens with the word "fortunately," so we know that he thinks it's a good thing none of them have been there. Plus, look at the word choice. Notice how the building is described. It's "by far the ugliest on the block," which is saying a lot since it's stuck between two burnt-out buildings. The writer calls it an "eyesore," and repeats "orange" with an exclamation point to emphasize how ugly the color is. Everything's "crooked" in this "poor excuse for a building." He's ashamed of where he lives and worries about what his friends would think if they saw it.

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