Central ideas and details

Digital SAT · Reading and Writing · Information and Ideas. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

These questions ask for one of two things: the main idea of a text, or a detail that the text states.

The main idea is the point the whole text makes. It covers every sentence, not only one of them. Ask: what is the topic, and what does the author say about it? Often an older or popular view comes first, and the author's real point follows a turn word such as "but" or "however."

For a detail question, find the words of the question in the text and read that sentence with care. The right option says the same thing in other words. In a story or poem, ask what the lines show about the character or the feeling.

Rules to remember

Main idea = the topic + what the author says about it.
A main-idea answer must cover the whole text, not one sentence of it.
Too narrow: true, but only a detail. Too broad: goes beyond the text. Both are wrong.
After "but," "however" or "yet," expect the author's real point.
Detail answer: stated in the text, usually in different words (a paraphrase).
Reject any option that makes a claim the text never makes, even if it is true in real life.

Common mistake

Choosing an option that the text does state but that is only one detail, when the question asks for the main idea. Test your choice against the first sentence and the last sentence.

Worked example

"Bats are often feared, yet they are useful to farmers. A single bat can eat hundreds of insects in an hour, and some species pollinate fruit trees. Farms near bat caves often need less pesticide." Which is the main idea: (A) a bat can eat hundreds of insects in an hour, or (B) bats help farmers in several ways?

Topic: bats. The turn word "yet" leads to the author's point: they are useful to farmers.
The sentences on insects, pollination and pesticide all support that point.
(A) is stated in the text but covers one sentence only, so it is a detail.

Answer: (B) Bats help farmers in several ways.

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