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Central ideas and details

Identify the main point of a short passage or locate a specific detail the passage actually states.

Information and IdeasReading and Writing
Practice central ideas and details free

What the SAT actually asks

You read a short passage, usually one paragraph, and either state its main idea or find a stated detail. Main idea questions want the claim the whole passage supports, not the most interesting sentence in it. Detail questions ask what the text says about a specific person, study, or term, and the correct answer restates something in the passage in different words. Wrong answers are usually true statements that cover only part of the passage or go beyond it.

Information and Ideas is about 26 percent of the 54 reading and writing questions, and central ideas and details usually make up roughly 3 to 5 of them.

Where students lose points

How to attack these questions

  1. 1Summarize the passage in one short sentence in your own words before you look at the choices.
  2. 2For detail questions, find and underline the sentence that answers it, then match that sentence against each option.
  3. 3Eliminate any choice containing a claim you cannot point to a specific line for.

Example questions

Written for this skill, with the answer explained. 194 more are in the app.

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Central ideas and details
Real question

Farmers in the valley had long assumed that the dark, crumbly soil in their oldest fields owed its richness to the manure spread there for generations. Soil microbiologist Idil Warsame measured carbon in forty fields and found that manure history explained little of the variation. What tracked the dark soil closely was a deep-rooted native grass left standing in the field margins. Its roots, Warsame reports, carry carbon two meters down, where microbes break it apart slowly. The richness the farmers credited to their own labor is mostly the work of a plant none of them planted on purpose.

Which choice best states the main idea of the text?

Medium

Legal historian Amina Belkacem examined 600 petitions filed by women in nineteenth-century Algerian courts. Formal law gave these petitioners few grounds to challenge a male relative's control of family property. Belkacem found that the successful petitions almost never argued about rights. Instead they documented the relative's failure to maintain the household, a duty the same law attached to his authority. The petitioners won by holding the system to its own terms.

Which choice best states the main idea of the text?

  • A) Women petitioners lost cases by making claims about rights instead of invoking male relatives' household maintenance obligations.
  • B) Women petitioners succeeded by invoking the obligations built into male authority rather than claiming rights. ✓
  • C) Belkacem discovered that Algerian law granted women more rights than male relatives possessed in practice.
  • D) The majority of petitions filed by women in nineteenth-century Algerian courts failed to succeed in their legal arguments.

Why: Belkacem's finding is that the successful petitions "almost never argued about rights" and instead documented the male relative's failure at a duty the same law attached to his authority, so the petitioners "won by holding the system to its own terms." "Belkacem discovered that Algerian law granted women more rights than male relatives possessed in practice." reverses the legal setup, since the passage says formal law gave these petitioners "few grounds" to challenge a relative's control. "Women petitioners lost cases by making claims about rights instead of invoking male relatives' household maintenance obligations." converts a statement about what won into a claim about what lost; the passage reports the content of the successful petitions and never says that rights arguments were the reason other petitions failed. "The majority of petitions filed by women in nineteenth-century Algerian courts failed to succeed in their legal arguments." puts a proportion on the outcomes that the text does not give, since 600 petitions are examined but no success rate is reported.

Harder

Ozone in the city's air fell sharply after diesel limits took effect, but only on weekdays. Weekend ozone rose. Atmospheric chemist Salome Tadesse's monitors show why the two can move apart: diesel exhaust both makes ozone and destroys it, and which effect dominates depends on how much of it there is. Above a threshold the exhaust scavenges ozone faster than it generates it. Weekday traffic had been sitting above that threshold; weekend traffic never did. Cutting diesel lowered a ceiling on weekdays and removed a floor on weekends, from one change in the fuel rule.

Which choice best states the main idea of the text?

  • A) Weekend traffic in the city has always been lighter than weekday traffic is.
  • B) Diesel exhaust destroys ozone faster than it produces it above a threshold level.
  • C) The city's diesel limits failed to improve air quality across the region as a whole.
  • D) One rule change cut weekday ozone and raised weekend ozone, across a threshold. ✓

Why: The text's claim is spread across its parts: ozone fell on weekdays and rose on weekends, diesel both makes and destroys ozone, and weekday traffic alone sat above the threshold. Choice B is that middle mechanism alone. Choice C supplies a net judgment the text never offers. Diesel exhaust destroys ozone faster than it produces it above a threshold level. is the chemistry the text supplies in order to explain a split result, not the result itself. Weekend traffic in the city has always been lighter than weekday traffic is. is a background fact the text implies rather than the point it is making. The city's diesel limits failed to improve air quality across the region as a whole. is a verdict the text does not reach; it reports opposite effects, not a net failure.

Harder

Philosopher Kwame Anthony Appiah has argued against what he calls "cultural purity" — the idea that cultures are fixed, bounded entities that must be preserved in their original form. Instead, Appiah contends that all cultures have always borrowed from one another, and that this exchange is a source of vitality rather than contamination. He points to examples ranging from the adoption of Arabic numerals in Europe to the global spread of jazz, arguing that cultural interaction typically enriches rather than diminishes the participating cultures.

The passage suggests that the concept of cultural purity is problematic primarily because it

  • A) assumes that cultures can remain unchanged when in fact all cultural products eventually spread across different regions
  • B) misrepresents the historical relationship between cultures by ignoring the reality that cultural borrowing has always occurred ✓
  • C) prevents cultures from adopting beneficial practices like Arabic numerals and jazz that have proven their value globally
  • D) treats cultural exchange as contamination rather than as a process that typically strengthens the cultures involved

Why: Appiah's ground for rejecting cultural purity is historical, that 'all cultures have always borrowed from one another,' with Arabic numerals in Europe and the global spread of jazz as cases, so a view of cultures as fixed and bounded gets the past wrong: misrepresents the historical relationship between cultures by ignoring the reality that cultural borrowing has always occurred. The text makes no forecast that cultural products will spread, only a claim about borrowing that has already happened: assumes that cultures can remain unchanged when in fact all cultural products eventually spread across different regions. The numerals and jazz appear as evidence that borrowing occurs and enriches, not as practices the idea of purity blocked: prevents cultures from adopting beneficial practices like Arabic numerals and jazz that have proven their value globally. And this restates the value side of Appiah's case, exchange as vitality rather than contamination, which is his answer to the idea rather than the historical error in it: treats cultural exchange as contamination rather than as a process that typically strengthens the cultures involved.

Questions students ask

How do I find the central idea of an SAT passage?

Ask what claim every sentence in the passage is helping to support. The central idea covers the whole passage, not just the most detailed or most memorable sentence. Summarizing in your own words first makes wrong choices much easier to eliminate.

Why do wrong answers on main idea questions often sound right?

Because they usually are true, just not central. A common wrong answer describes one supporting detail accurately and presents it as the point of the passage. Checking whether a choice accounts for the whole passage separates it from the correct one.

Should I read the passage or the question first?

Read the question first on the digital SAT, since each passage has only one question attached. Knowing whether you need the main idea or one specific detail changes how you read the short passage and saves time.

Drill this skill until it is automatic

Questions on central ideas and details alone, with explanations on every one, and the app tracks which ones you keep missing.

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