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Identify central ideas, themes, and supporting details in passages. Summarize texts accurately and determine how details develop key concepts.
Learn step-by-step with practice exercises built right in.
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A passage begins with an anecdote about a farmer losing crops to drought, then discusses climate change impacts on agriculture globally. What is the central idea?
Finding the central idea:
The anecdote (farmer losing crops) is a specific example used to introduce a broader topic.
The passage then zooms out to discuss climate change impacts on agriculture GLOBALLY.
Central idea: Climate change is significantly affecting agriculture worldwide.
Why the anecdote is NOT the central idea:
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Strategy: Ask yourself: "If I had to summarize this passage in ONE sentence, what would it be?"
Common trap: Choosing an answer that is too specific (about the one farmer) or too broad (about climate change in general, not specifically agriculture).
Answer: The central idea is that climate change poses a significant threat to global agriculture.
How do you distinguish a central idea from a supporting detail?
The Two-Question Test:
Can the passage exist without this point?
Does this point support something bigger?
Examples from a passage about the benefits of exercise:
Hierarchy: Central Idea → Major Supporting Points → Details/Evidence/Examples
SAT Tip: The central idea is usually stated or implied in the first or last paragraph. Supporting details appear in body paragraphs.
A question asks: "Which choice best states the central idea of the passage?" Answer choices are: (A) Scientists should receive more funding. (B) The scientific method has evolved significantly over the past century. (C) Modern technology has improved laboratory techniques. (D) Peer review is essential to good science. The passage discusses the history of the scientific method. Which is correct?
Evaluate each choice against the passage topic (history of the scientific method):
(A) "Scientists should receive more funding" → This is an opinion/recommendation, not a historical discussion. Doesn't match. ❌
(B) "The scientific method has evolved significantly over the past century" → This directly addresses the HISTORY and DEVELOPMENT of the scientific method. Matches the passage topic! ✅
(C) "Modern technology has improved laboratory techniques" → Too narrow — focuses only on technology/labs, not the broader scientific method. ❌
(D) "Peer review is essential to good science" → Too narrow — peer review is just one aspect of the scientific method. ❌
Answer: (B) — It captures the full scope of the passage (evolution of the scientific method) without being too narrow or off-topic.
SAT Tip for central idea questions:
A passage discusses how ancient civilizations developed writing systems. Paragraph 1 covers Sumerian cuneiform, Paragraph 2 covers Egyptian hieroglyphics, Paragraph 3 covers Chinese oracle bones, and Paragraph 4 argues they developed independently. What is the central idea vs. the supporting details?
Central Idea (Paragraph 4): Multiple ancient civilizations developed writing systems independently of each other.
Supporting Details:
Why the central idea is in Paragraph 4:
Structure analysis: This passage uses an inductive structure — specific examples first, then the general conclusion they support.
(The opposite would be deductive: claim first, then evidence.)
Answer: The central idea is that writing systems arose independently across civilizations. The descriptions of cuneiform, hieroglyphics, and oracle bones are supporting details that illustrate this conclusion.
A complex passage discusses economic inequality, mentioning the Gini coefficient, historical tax policies, wage stagnation, and social mobility data. The passage has a nuanced argument. How do you identify the central idea when a passage is complex?
Strategy for complex passages:
Step 1: Read the first and last paragraphs carefully. These almost always contain the thesis (first) and conclusion (last).
Step 2: Identify the throughline. What theme connects ALL the paragraphs?
Throughline: Economic inequality — its measurement, causes, and effects.
Step 3: Determine the author's POSITION. Is the author:
Step 4: Craft the central idea as a single sentence. "Growing economic inequality, driven by tax policies and wage stagnation, has significantly reduced social mobility in America."
Step 5: Match to the best answer choice. Eliminate choices that:
Answer: For complex passages, synthesize the themes from multiple paragraphs into one overarching claim that the author is making.