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Reading & WritingChapter 3: Command of Evidence

Notes

Evidence That Supports or Weakens a Claim Notes

Determine whether relevant evidence raises, lowers, or leaves unchanged a claim's credibility.

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Evidence has direction. Supporting evidence makes a claim more credible; weakening evidence makes it less credible; neutral evidence does not meaningfully change it.

What the SAT is testing

Command of Evidence
A supplied claim or point is evaluated with the textual or quantitative evidence that best supports, illustrates, weakens, or challenges it.

Core concept

For a causal claim, ask whether the finding tests the proposed cause-and-effect link. Evidence for a competing mechanism can weaken the original explanation even when the original observation remains true.

Evidence distinctions

Support

Matches a prediction made by the claim. Example: Treatment changes the outcome in the predicted direction.

Neutral

Does not bear on the predicted relationship. Example: The equipment has a different color.

Weaken

Contradicts a prediction or favors an alternative. Example: The comparison group changes equally.

Step-by-step strategy

Claim-first evidence method

  1. Identify

    State the exact claim, including its population, condition, direction, and qualification.

  2. Predict

    Ask what evidence would look like if the claim were true—or what would challenge it.

  3. Locate

    Select only the text or data relevant to that predicted relationship.

  4. Compare

    Evaluate direction, scope, directness, and required assumptions across choices.

  5. Verify

    Check the chosen wording and every cited value against the stimulus.

Worked example

Worked example

Apply 3-3

A team hypothesizes that a plant extract discourages beetles specifically because of its scent.

Question: Which finding would most directly weaken the hypothesis?

  1. Beetles avoided scentless extract-coated leaves just as often as scented extract-coated leaves.
  2. The extract's scent remained detectable for two hours.
  3. Beetles approached untreated leaves more often than scented treated leaves.
  4. The extract was produced from locally grown plants.
  1. Step 1

    The claim is not merely that the extract works; it identifies scent as the mechanism.

  2. Step 2

    Equal avoidance of scentless and scented versions shows that scent is not needed for the observed behavior.

  3. Step 3

    Choice C supports avoidance, while B and D do not test the mechanism.

Choice A weakens the proposed scent mechanism.

Why each choice works or fails

  1. Correct: it preserves the effect while undermining the proposed cause.
  2. Neutral: scent duration does not show whether scent causes avoidance.
  3. Wrong direction: this supports an effect of the scented treatment.
  4. Irrelevant: production location does not test beetle behavior.

Common traps and wrong-answer patterns

Mini check

Mini check

Claim: reminders increase attendance. Which finding most weakens it?

  1. Attendance was 71% with reminders and 72% without them.
  2. Reminders were sent one day before each event.
  3. Students said the reminder font was clear.
  4. More events occurred in spring than fall.
Show answer and explanation

Answer: A

The nearly identical attendance rates contradict the predicted group difference.

Key takeaways

Key takeaways

What to remember

  • Direction matters only after relevance is established.
  • Support increases credibility; weaken decreases it; neutral does neither.
  • Contrary, null, and alternative-mechanism findings can weaken claims.
  • Do not inflate support into proof or weakening into disproof.
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Put these notes into practice

Apply the ideas with SAT-style questions, then reinforce key details with flashcards.