University admissions preparation Main Purpose and Central Claim

In the digital SAT's Reading & Writing section, questions use short passages or passage pairs: across the two modules there are 54 questions in total, and each module gives you 27 questions in 32 minutes — so the average is about 70 seconds per question. This is not a separate time limit for each question; allocate time according to need. These questions test understanding of function, not speed-reading.

You need to recognize two question types immediately:

• Main purpose: the question reads Which choice best states the main purpose of the text? It measures why the author wrote, and it belongs to the Craft and Structure domain.
• Central claim / main idea: Which choice best states the main claim of the text? It measures what the author claims, and it belongs to the Information and Ideas domain.

Choices can be phrases or complete sentences; read the exact question requirement. In this lesson you will practise distinguishing question types, using the first and last sentences as a starting anchor checked against the whole text, and rejecting unsupported options with evidence.

These three concepts do different jobs:

• Purpose is function: for what purpose did the author write this text? The answer is usually an infinitive phrase: to challenge a popular assumption, to explain a process, to evaluate a proposal.
• Claim is position: what does the author hold to be true? The answer is a complete statement of an idea: City trees function as cooling infrastructure.
• Summary is a compact restatement of the content; it should capture the general message, not specific examples.

Practical tip: choices beginning with to... can fit a purpose question, but the grammatical form of a choice does not determine the question type by itself. Read the whole question to know the requirement.

For a purpose question identify what the author is doing; for a claim question identify the central idea. Do not substitute one supporting detail for the overall message, but do not ignore a name, date or number if it is an essential part of the central claim.

Key verb bank:

The first and last sentences can be a starting anchor, but the main idea may also appear in the middle. Read and check the whole short text and the relationships between its ideas. You can practise this habit as follows:

1. Read the first sentence — identify the topic or view introduced; do not assume it is always an old accepted belief.
2. Check whether the last sentence contains a turn or conclusion; it is not always located there. Transitions such as However, but, in fact, therefore, thus, as a result mark the real emphasis of the text.
3. Build a one-sentence summary in your own words: The author says ... about ....
4. Look at the options and choose the one closest in meaning; an option that simply repeats the words of the text is not always right.

Demo — first sentence: For decades, scientists treated octopuses as strictly solitary hunters. Last sentence: Recent footage shows, however, that some octopuses cooperate. Anchor thought: the text overturns an old belief.

Middle sentences may supply the central claim, essential evidence or a limitation; do not skip them. You need not memorise every detail, but check the initial summary against the entire text and reread the relevant part when needed.