Main Idea and Purpose

• Identify main-idea questions from their phrasing ('primary purpose,' 'main point,' 'best summary')
• Locate the main idea using the first and last paragraphs and topic sentences
• Distinguish author's purpose ('to persuade,' 'to inform,' 'to criticize') from main idea (what the passage is about)
• Eliminate main-idea answer choices that are too narrow (a single paragraph) or too broad (outside the passage scope)
• Spot the 'partial truth' trap: an answer that is true about part of the passage but not the whole

Main-idea questions ask what the passage is about as a whole. Author's-purpose questions ask why the author wrote it. They feel similar but test different things. Main-idea wording includes 'main idea,' 'main point,' 'central idea,' 'best summarizes,' or 'the passage is primarily concerned with.' Author's-purpose wording includes 'main purpose,' 'primary purpose,' 'mainly serves to,' 'primarily functions to,' or 'most likely mentions ... in order to.' (A question about 'the author's attitude toward' something is a tone question.) ACT asks both about whole passages and about one paragraph, citing its lines: 'The main point of the third paragraph (lines 22-35) is that' and 'The main purpose of the fifth paragraph (lines 40-52) is to'. For ACT literary narrative passages, the main idea is usually about a character's internal change or a relationship. For social science and natural science, it is usually about a concept, process, or argument. For humanities, it is often about an artistic or cultural insight. Answer main-idea questions after the specific questions on a passage: the specific questions teach you the passage first. The main idea often lives in the first paragraph (sometimes the last), in the topic sentence, but check it against the whole passage, because an opening paragraph can set up a view the passage then turns away from. If the first paragraph sets up a question, the rest of the passage answers it, and the main idea is that answer. The act's favorite wrong-answer patterns on these questions: (1) Too narrow. The choice describes a single paragraph or example rather than the whole passage. (2) Too broad. The choice goes beyond the scope of the passage. (3) Partial truth. The choice mentions something from the passage but misrepresents its role (e.g., labels a minor detail as the main focus). (4) Opposite. The choice reverses the author's actual stance. (5) Out of scope. The choice introduces an idea the author never discussed. For author's-purpose questions, the verb matters: 'criticize' and 'defend' are strong; 'describe' and 'explain' are neutral. Match the verb to the passage's overall tone. If the author is balanced, 'criticize' is wrong even if a critical sentence appears.

• Read the first and last paragraphs twice. The main idea almost always lives there.
• Before looking at answer choices, write a 5-word summary of the passage in your own words. Then find the choice that matches.
• If an answer describes only one paragraph, it is too narrow. Eliminate it.
• Match the intensity of the answer's verb (criticize, defend, explore, reject) to the passage's actual tone.
• When two choices feel close, ask which one covers more of the passage. The broader accurate one usually wins.