Analyzing the Purpose and Central Idea | The Complete SAT Course - Class 10 PDF Download

Finding the Purpose

About 20–30% of SAT CR questions are “purpose” questions, such as “The overall purpose of this passage is to . . . .” or “The author refers to the ‘mountaintop’ in line 6 in order to emphasize. . . .” These questions ask why the author wrote the passage or used a particular word, phrase, or reference. You will always be prepared for these questions if you focus on overall purpose as you read.

SAT CR passages are drawn from a wide range of disciplines, but every passage has only one of three possible purposes:

• To examine a concept objectively. A passage that examines a concept is an analysis. It is strictly informative, like a newspaper article or a textbook passage. Think of it as a response to an essay question. It is objective—sticking to facts rather than opinions. 
• To prove a point. A passage that proves a point is an argument. It presents the author’s point of view on a topic and explains why it is better than another point of view. It is subjective—a matter of opinion rather than fact.
• To tell a story. A passage that tells a story is a narrative—a piece of fiction, a biography, or a memoir. It describes how a character changes in order to deal with a conflict or problem. 

To understand a passage, begin by asking, “Is this passage an analysis, an argument, or a narrative? Is its main purpose to inform to persuade, or to inform?” Knowing this makes answering many SAT questions easier.

Often, the introduction to the passage gives you clues about the purpose. Look for key words such as these: 

• Analysis key words: examine, analyze, scientific, historical, explore 
• Argument key words: comment, argue, opinion, perspective, point of view, position 
• Narrative key words: biography, story, autobiography, memoir, novel, fiction, account

Finding the Central Idea

Often, the first question after an SAT passage is a “central idea” question such as “With which of the following statements would the author most likely agree?” or “This passage is primarily concerned with. . . .” Knowing the central idea is critical to answering these questions. When you are given two “paired” passages, it is particularly important to know how their central ideas compare and contrast. 

Although SAT passages contain lots of ideas, each has only one central idea. Find it. Every different type of prose has a different type of central idea.

• Every analysis focuses on a question that might interest a college professor. It might answer a question such as “What methods do scientists use to measure the location and intensity of earthquakes?” or “What were the social conditions of women in 19^th-century England?”
•  Every argument focuses on a thesis—the point the writer is trying to make. An argument takes a side and makes an evaluation. It argues against something substantial and doesn’t merely support a claim that everyone already agrees with. Too many students forget this. When reading an argument, ask “What substantial idea is this author arguing against?” 
• Every narrative focuses on a conflict—the problem that the main character must deal with. There is no story without conflict—conflict drives the story. Basically, every story consists of (1) the introduction of the conflict, (2) the development of the conflict, and (3) the resolution of the conflict. Understanding a story begins with understanding this structure.

Once you discover the purpose of the passage, find its central idea—the question, the thesis, or the conflict. Underline it in the passage or jot it down in the margin. To make sure that you really have the central idea, check that it is supported by every paragraph. Often, students mistakenly think that the first idea in the passage must be the central idea. Not necessarily.

For instance, an author may describe an opposing viewpoint before presenting his or her own, so his or her central idea doesn’t appear until the second or third paragraph.