Finding an Implied Main Idea Study Guide (page 2)
Practice exercises for this study guide can be found at:
This lesson shows you how to find the main idea when there's no topic sentence or thesis statement to guide you. It also explains how to find a theme, the main idea in literature.
Oh, the power of suggestion! Advertisers know it well—and so do writers. They know they can get an idea across without directly saying it. They know that they don't always need a topic sentence because they can use structure and language to suggest their ideas.
What is a main idea? It is a claim (an assertion) about the subject of the passage. It's also the thought that holds the whole passage together. Thus, it must be general enough to include all the ideas in the passage. Like a net, it holds everything together. Main ideas are often stated in topic sentences.
So far, most of the passages in this book have topic sentences. But you'll often come across passages that don't have topic sentences. Writers often imply ideas instead of stating them directly. To imply means to hint or suggest. You'll need to use your powers of observation to determine their message.
How to Find an Implied Main Idea
When the main idea is implied, there's no topic sentence, so finding the main idea requires some good detective work. But you already know the importance of structure, word choice, style, and tone. You know how to read carefully and find clues, and you know that these clues will help you figure out the main idea.
For example, take a look at the following paragraph:
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?
- Toby wishes he could move to a nicer building.
- Toby wishes his dad still lived with them.
- Toby is glad none of his friends know where he lives.
- 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. Sentence (choice d) isn't 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 terribly 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.
Casting a Net
When you're looking for an implied main idea, what you're really doing is searching for the right "net" to cast over the passage. What is the idea that encompasses all the other ideas in the passage? What holds it together? (Remember, a paragraph, by definition, is a group of sentences about the same idea.)
What if you're looking for the main idea of several paragraphs? Well, it's really the same thing. Instead of determining the main idea of an individual paragraph, you're determining the overall main idea. Remember the comparison between a table and an essay? In an essay, the overall main idea is the tabletop, while the supporting ideas are the legs that hold up (support) the table. Each of those legs, though, might be paragraphs of their own with their own main idea and supporting sentences.
Here's a very short essay with an implied main idea. Read it carefully. Can you see what the whole passage adds up to?
It has been more than 25 years since the National Aeronautic and Space Administration (NASA) last sent a craft to land on the moon. A lunar prospector took off in January 1998, in the first moon shot since astronauts last walked on the moon in 1972. This time, the moon-traveler is only a low-cost robot that will spend a year on the surface of the moon, collecting minerals and ice.
Unlike the moon shots of the 1960s and 1970s, the lunar prospector does not carry a camera, so the American public will not get to see new pictures of the moon's surface. Instead, the prospector carries instruments that will map the makeup of the entire surface of the moon.
Scientists are anxious for the results of the entire mission and of one exploration in particular—that done by the neutron spectrometer. Using this instrument, the prospector will examine the moon's poles, searching for signs of water ice. There has long been speculation that frozen water from comets may have accumulated in craters at one of the moon's poles and may still be there, as this pole is permanently shielded from the sun.
Which of the following statements seems to best express the overall main idea of this passage?
- There is a great deal we can learn from studying the moon.
- The prospector will collect surface data rather than take pictures.
- NASA's newest moon-traveler is on an important mission.
- Scientists hope the prospector will return with evidence of water on the moon.
If you remember that a main idea must be general enough to hold the whole passage together and that a main idea must also be an assertion about the subject, then it should be pretty easy to tell which is the correct answer. First, choices b and d are too specific to be the main idea; they deal only with information in the second and third paragraphs, respectively. Second, they state only facts; they don't make a claim about the subject.
They can't be the overall main idea for this passage. Choices a and c, on the other hand, both make assertions about the subject and are general. Notice how they both allow room for detailed support. But while choice a casts a wide enough net, it's not the right net for this passage. The passage is about what NASA hopes to learn from this specific mission. So while choice b and choice d are too specific, choice a is too general to be the main idea of this passage. "NASA's newest moon-traveler is on an important mission," however, casts a net that's just the right size, thus choice c is the correct answer.
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