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SAT: Function of the Underlined Sentence

A function question underlines one sentence and asks what it does in the passage. The answer choices all start with a verb: introduces, illustrates, qualifies, challenges, provides context. Your job is to pick the verb that matches the sentence's role, which is a different question from what the sentence means.

The rule

Answer what the sentence does for the passage, not what the sentence says.

Function is defined by surroundings, so read the sentence before and the sentence after the underlined one. A sentence that gives a number is doing nothing on its own. If the sentence before it made a claim, the number is evidence. If the sentence after it says however, the number is a setup for a contrast. The same sentence can have different functions in different neighborhoods.

Convert each answer choice into a question about the passage. Illustrates a claim asks whether there is a claim nearby being illustrated. Qualifies a previous statement asks whether an earlier statement is being narrowed. Introduces a counterargument asks whether an opposing view follows. Then check whether the passage actually contains that thing.

The most common wrong answer summarizes what the sentence says rather than what it does. If the underlined sentence describes a lab result, a choice reading describes the outcome of the experiment is a summary, not a function. Functions connect the sentence to the rest of the text, so a choice that could be written without reading anything else is suspicious.

The second pattern to watch is a right verb attached to a wrong object. A choice saying the sentence provides evidence for the author's central claim may have the right verb while naming a claim the author never made. Verify both halves separately: does the sentence do that action, and is the thing it acts on actually present.

For whole-passage structure questions, sketch the shape in three or four words as you read, such as belief, then challenge, then new explanation. Then find the choice that traces the same path in the same order. A choice describing the right elements in the wrong sequence is a standard wrong answer and is easy to catch once you have your own outline.

The trap

Picking a choice that accurately summarizes the underlined sentence's content while naming no role it plays in the text.

Try it

Try one
Real question

A juvenile octopus can solve a maze it has never seen. It can also open a jar, once. Researchers who test the same animal a week later find that it must work the problem out again from the beginning, and that an animal which first opened a jar in ninety seconds will take nearly as long on its second attempt. Octopuses are widely described as intelligent, and by most measures they are. What they appear to lack is a way of carrying a solution forward in time.

Which choice best describes the function of the sentence "Octopuses are widely described as intelligent, and by most measures they are" in the text as a whole?

Flight recorders survive crashes because they are built to, and engineers list the qualities: a steel shell, thermal insulation, a fixed position in the tail. The list is misleading in one respect. Survival is not a property of the box but of the pairing between the box and the accident, and the tail is safest only in impacts where the aircraft strikes nose first. In water landings and in-flight breakups, the same position is among the worst available. Investigators choose the position that fits the likeliest accident.

Which choice best describes the overall structure of the text?

  • A) It recommends that flight recorders be relocated from the tail of an aircraft to a more survivable position.
  • B) It describes the construction of a flight recorder and then argues that one description of it is imprecise. ✓
  • C) It contrasts flight recorders designed for water landings with those designed for impacts at high speed.
  • D) It lists the features engineers build into a flight recorder so that the device will survive a crash intact.

Why: The text lists the recorder's features, says "The list is misleading in one respect," and shows that the tail's safety depends on the kind of impact. Choice D restates the list the text then qualifies. Choice A suggests a relocation the text never proposes, since no safer position is named. Choice C invents two designs where the text describes one. It contrasts flight recorders designed for water landings with those designed for impacts at high speed. is one design is described; the contrast is between accident types, not designs. It recommends that flight recorders be relocated from the tail of an aircraft to a more survivable position. is no better position is identified, and none is recommended. It lists the features engineers build into a flight recorder so that the device will survive a crash intact. is true of the first sentence, which the rest of the text calls misleading.

Practice more of these free

Questions students ask

How much of the passage should I reread?

At minimum the sentence before and the sentence after the underlined one, since function is a relationship. If the choices refer to the passage's main claim, you also need to know what that claim is, so a quick scan of the opening and closing lines helps.

What do words like qualify and undercut mean in these choices?

To qualify a statement is to narrow it or add a condition, not to reject it. To undercut is to weaken it. To concede is to admit a point in the other direction before continuing. These verbs are the actual content of the answer choices, so knowing them precisely matters.

Guides that cover this

More on text structure and purpose