Central ideas and details on the SAT: lesson and practice
The main idea is the point that every sentence supports. Summarize the text in one sentence before reading the choices, then pick the choice that matches. Wrong answers are usually a single detail (too narrow), a claim bigger than the text (too broad), something the text never says, or something that contradicts it.
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A three-step method
- Read the whole text. Pay special attention to the last sentence and to words like however and therefore.
- Summarize it in your own words in one short sentence.
- Match your summary to a choice, then check every part of that choice against the text.
The four traps
| Trap | What it looks like |
|---|---|
| Too narrow | Repeats one detail from one sentence |
| Too broad | Uses "all", "always", or talks about a whole field |
| Not in the text | Sounds true, but the text never says it |
| Contradicts the text | Reverses a key detail |
Common mistakes
Sample questions with answers
1. Honeybees keep their hive near 35°C: they fan warm air out on hot days and cluster and shiver on cold days. Main idea?
- Worker bees fan their wings at the entrance.
- Honeybees use different behaviors to control hive temperature. (correct)
- Bees are more active on hot days.
- Young bees cannot survive outside the hive.
Every sentence explains how bees control temperature.
2. Many students reread notes, but research suggests self-testing helps memory more. Main idea?
- Rereading is the best method.
- Testing yourself may help memory more than rereading. (correct)
- Exams should be replaced.
- Students never reread notes.
The point after "however" is the main idea.
3. A historian says the printing press mattered because it made identical copies, not because books were cheap. What is her view?
- Books became cheap.
- The press produced identical copies scholars could share. (correct)
- Scholars disagreed.
- Everyone could afford books.
Her "different view" is the focus of the text.
Frequently asked questions
How many central idea questions are on the SAT?
Central ideas and details are part of Information and Ideas, which makes up about 26% of the Reading and Writing section, roughly 12 to 14 questions.
How do you find the main idea quickly?
Read the whole short passage, paying attention to the last sentence and contrast words, and summarize it in one sentence before reading the choices.
Why is a true detail sometimes the wrong answer?
Because a main idea question asks for the point of the whole text, not one fact from it.
Should I use my own knowledge?
No. SAT answers must be supported by the text alone.