State the main idea of a passage or locate a detail that the passage actually supports. It is part of Information and Ideas in the Reading and Writing section. The book teaches it in Chapter 8, Central Ideas and Details, with 15 practice questions, and tests it 6 more times across the two full-length practice tests.
About Chapter 8
Information and Ideas is the second content domain in each Reading and Writing module, after Craft and Structure. Its questions ask what a text says, what evidence supports a claim about it, and what follows logically from it. Central Ideas and Details questions usually open the group, and they are the most direct reading task on the test.
The correct choice is nearly always the passage restated in different words. The wrong choices borrow its vocabulary, stretch its claims or cover only one corner of it.
What the question looks like
Each question gives you one passage of 25 to 150 words, literary (prose or poetry) or informational (science, history, social studies or the humanities), and asks one of three things.
Which choice best states the main idea of the text?: The point the whole passage makes
According to the text, why (or what, or how)...?: One detail the passage states directly
Based on the text, what is true about [a person or thing]?: A detail or trait the passage clearly shows, common with literary texts
Main idea questions want the whole passage in one sentence. Detail questions want one fact, usually tied to a word in the stem: a group, a cause, a result, a surprise. Either way, you can point to the words that prove the answer. Outside knowledge never rescues a choice.
How to recognize it
Sort short-passage questions by what the stem asks you to do.
If the stem asks what the text says, it is Central Ideas and Details.
If it asks what the text does (the function of a sentence, the purpose or structure of the whole), it is Text Structure and Purpose (Chapter 6).
If it asks which quotation, finding or data would support or weaken a claim, it is Command of Evidence (Chapter 9).
If the passage ends with a blank and the stem asks which choice most logically completes the text, it is Inferences (Chapter 10).
The standard of proof differs. For Central Ideas, the answer is in the passage, reworded; for Inferences, it follows from the passage but is not written there. If you are reasoning several steps beyond the text on a main idea question, you have probably drifted into a trap.
Common traps
Too narrow; What it looks like: A true detail from one sentence, often the background; How to spot it: Ask whether the rest of the passage is about it
Too broad; What it looks like: A claim larger than the passage’s subject or scope; How to spot it: Look for all, every, always or a bigger field
Half right; What it looks like: A correct first half joined to an unsupported second half; How to spot it: Read every word; one false clause kills a choice
Recycled words; What it looks like: Passage vocabulary rearranged into a new claim; How to spot it: Point to the sentence; matching words are not matching meaning
The common view; What it looks like: The opinion the passage sets up in order to challenge; How to spot it: Find the turn and read what follows it
Outside knowledge; What it looks like: True in the world but not stated in the passage; How to spot it: If you need anything beyond the text, reject it
Invented feeling; What it looks like: A character’s emotion, motive or plan the text never shows; How to spot it: Find the words that show it; if none exist, eliminate
Video lessons
Two short lessons from independent YouTube creators, chosen for this skill. The notes are ours; the videos belong to their creators, who are not affiliated with this site.
Central ideas and details, worked through (Penguin SAT Prep , 19:18). Watch for: Separating the main claim from supporting detail in a short passage.
Finding the central idea quickly (The Digital Tutor | Learn Today. Lead Tomorrow., 6:27, captions). Watch for: Summarizing the passage in your own words before you read the choices.
Practice this skill
The full method, worked examples and 15 practice questions with every answer choice explained are in Chapter 8 of the book and in the study workspace, where an AI coach can talk you through each one.
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