Craft and Structure · Reading & Writing

Text Structure and Purpose

Questions about why a text is built the way it is: the main purpose of the whole passage, or the function of one underlined part within it. You are describing the author's move, not summarising the content.

40 questions in the bank · 8 easier · 21 medium · 11 harder · this domain is ≈28% of the section

Learn it in the Guide

What to watch for

A choice can be perfectly true about the passage and still be the wrong answer, because it describes what the text says rather than what it is doing. Prefer verbs that name a move — introduces, qualifies, illustrates, challenges.

How the question is worded

These are the actual stems used in the bank — the SAT reuses a small set of wordings, and recognising them saves time on test day.

  • Which choice best describes the function of the underlined sentence in the text as a whole?
  • Which choice best describes the function of the underlined sentence?
  • Which choice best states the main purpose of the text?
  • Which choice best describes the overall structure of the text?

Worked examples

easyRooftop greenhouses seem like an obvious way for cities to grow food, and thei…

Rooftop greenhouses seem like an obvious way for cities to grow food, and their vegetables do travel mere floors, not continents, to reach eaters. [[Yet a greenhouse perched on a roof must be heated through winters that a field never asks a farmer to heat.]] Studies that tally full energy budgets find some rooftop operations consuming more energy per tomato than the trucked-in alternative.

Which choice best describes the function of the underlined sentence in the text as a whole?

  • A. It offers a rooftop greenhouse whose results confirm the advantage described earlier.
  • B. It explains how conventional field farming might adopt a greenhouse's heating methods.
  • C. It introduces a complication that challenges the advantage described earlier.
  • D. It summarizes the energy findings that the studies mentioned later go on to report.

Answer: C. It introduces a complication that challenges the advantage described earlier.

Explanation

The sentence pivots with "Yet" from the shipping advantage to a heating cost fields don't have — a complication that sets up the energy-budget findings. It offers no example, doesn't summarize the studies (it precedes and motivates them), and says nothing about fields adopting greenhouses.

mediumThe luthier's workshop smells of spruce shavings and hide glue. Racks of half-…

The luthier's workshop smells of spruce shavings and hide glue. Racks of half-carved violin plates line one wall, each labeled with its wood's origin and age. [[Ask her why one blank of maple becomes a concert instrument while its neighbor becomes firewood, and she hands you both pieces and tells you to knock.]] The demonstration makes her point better than any lecture: one blank rings like a struck bell, the other thuds.

Which choice best describes the function of the underlined sentence?

  • A. It explains the chemical difference between resonant and non-resonant maple blanks.
  • B. It presents an anecdote that sets up the demonstration described in the next sentence.
  • C. It describes the workshop's layout so that the reader can picture where the racks stand.
  • D. It criticizes the luthier for refusing to give a straight answer about her materials.

Answer: B. It presents an anecdote that sets up the demonstration described in the next sentence.

Explanation

The sentence stages the knock test that the following sentence calls "the demonstration" — it's the setup. No chemistry is explained, the refusal to lecture is presented admiringly rather than critically, and the workshop layout belongs to the earlier sentences.

hardThe case for rewilding rivers usually leads with the fish. Dams out, salmon up…

The case for rewilding rivers usually leads with the fish. Dams out, salmon up: the arithmetic is photogenic and true. [[But a free-flowing river is also a conveyor of inconvenient sediment, and the gravel that nourishes spawning beds downstream once buried a marina's slips within two seasons.]] Honest advocates have learned to promise both the salmon and the dredging bills, because communities that discover the second promise on their own rarely forgive the omission.

Which choice best describes the function of the underlined sentence?

  • A. It refutes the claim that removing dams reliably brings salmon back to a river.
  • B. It shifts the passage's focus from inland rivers to the harbors at their mouths.
  • C. It acknowledges a cost of rewilding that supports the passage's argument for candor.
  • D. It provides the passage's central example of a river restoration that worked as planned.

Answer: C. It acknowledges a cost of rewilding that supports the passage's argument for candor.

Explanation

The sentence supplies the downside (sediment, buried slips) that the final sentence's argument — promise both benefits and bills — depends on. It never denies the salmon arithmetic ("true"), the marina is a cautionary cost rather than a success story, and the harbor detail serves the river argument.