SAT® · Reading and Writing: Craft and Structure
Main Purpose of a Whole Text
A short text has one main purpose: the single job the author built the whole passage to do, usually carried in one claim sentence while every other sentence supports, sets up, or corrects that claim.
A passage this short only has room for one job. It might report a finding, correct a misconception, question an explanation, or recommend an action, but it does only one of these, because every sentence has been chosen to serve that single aim. Your task is to find the sentence that carries the claim and then check that the other sentences feed it: background, evidence, a contrast, a result. If a sentence doesn't feed the claim, you've misread which sentence is the claim.
The method is to ask what each sentence is doing, not just what it's about. A sentence about hormone levels and a sentence about volunteer counts can both serve a claim that is really about whether a popular belief held up. Background sentences exist to make the claim land, not to share the main purpose with it. This is why the longest or most detail-heavy sentence is often not where the purpose lives; long sentences frequently exist only to set up a short one that turns the passage, correcting, limiting, or reframing what came before.
This skill sits right next to text structure, because finding the purpose means seeing the passage's shape: background then claim, or claim then evidence, or setup then correction. It also connects to the paired-text topic nearby, where you do this same move twice and then compare the two purposes against each other. Once you can name the one job a single text is doing, comparing two texts is just doing that twice and asking how the jobs relate.
Key terms
- Main purpose
- The single job the whole text is built to do, such as reporting, correcting, or questioning a claim.
- Claim sentence
- The sentence that states the point the rest of the text is organized to support.
- Turn
- The moment a text shifts from background or an opposing view to its actual point.
- Service sentence
- A sentence that exists only to support or set up the claim rather than to state it.
Watch it explained
- How it worksHow do you find the one sentence carrying a claim and read every other sentence as service to it?
- Worked exampleWalk me through the main purpose of a text that says posture effects are overstated, then reports a study finding none.
- Common mistakeWhy isn't the main purpose of a text the topic its longest sentence happens to be about?
- Going furtherWhat happens to main purpose when a text spends most of its length on a view the author rejects?
Check yourself
End of topic.