Central Ideas and Details

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:

• The farmer's story is a supporting detail (specific example)
• It serves to illustrate and introduce the broader argument
• The passage expands beyond this one case

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.

The Two-Question Test:

1. Can the passage exist without this point?

   • Yes → It's a supporting detail
   • No → It's likely the central idea

2. Does this point support something bigger?

   • Yes → It's a supporting detail
   • No (other points support IT) → It's the central idea

Examples from a passage about the benefits of exercise:

• "Exercise releases endorphins" → Supporting detail (explains HOW)
• "Regular exercise significantly improves mental health" → Central idea (the main claim)
• "A 2019 study found..." → Supporting detail (evidence)
• "30 minutes of daily walking..." → Supporting detail (specific recommendation)

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.

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:

• Eliminate answers that are too narrow (one detail)
• Eliminate answers that are too broad (beyond the passage's scope)
• Eliminate answers that introduce ideas not in the passage
• The correct answer encompasses the WHOLE passage

Central Idea (Paragraph 4): Multiple ancient civilizations developed writing systems independently of each other.

Supporting Details:

• Sumerian cuneiform (Paragraph 1) → Example 1
• Egyptian hieroglyphics (Paragraph 2) → Example 2
• Chinese oracle bones (Paragraph 3) → Example 3

Why the central idea is in Paragraph 4:

• Paragraphs 1-3 provide evidence (three specific examples)
• Paragraph 4 makes the argument these examples support
• The examples serve the larger claim about independent development

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.

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?

• Gini coefficient → measures inequality
• Tax policies → contribute to inequality
• Wage stagnation → a cause/effect of inequality
• Social mobility → a consequence of inequality

Throughline: Economic inequality — its measurement, causes, and effects.

Step 3: Determine the author's POSITION. Is the author:

• Describing a problem? (informational)
• Arguing for a solution? (persuasive)
• Analyzing causes? (analytical)
• Comparing perspectives? (evaluative)

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:

• Address only ONE aspect (just taxes, just wages)
• Miss the author's position (neutral when the author takes a stance)
• Are too general ("Economics is complicated")

Answer: For complex passages, synthesize the themes from multiple paragraphs into one overarching claim that the author is making.