Evidence must connect to the claim's exact relationship. A finding about the same topic can still fail to support it.
Textual Command of Evidence questions ask you to judge how a quotation or finding bears on a claim. Shared subject matter is insufficient: the evidence must support or weaken the relationship the question names.
Break the claim into its moving parts
Identify who or what is being compared, the outcome, and any condition. If the claim is “plants exposed to light treatment A grow taller than comparable plants exposed to B,” useful evidence must address growth and the comparison. A finding that A is inexpensive says nothing about the claimed difference in height.
Check whether the task asks for support or weakening before evaluating the choices. A finding can be informative without doing either strongly. You are selecting evidence, rather than merely paraphrasing the text.
Worked example: the comparison matters
This is an original teaching exercise, not a released SAT question.
A botanist hypothesises that, under otherwise similar conditions, seedlings exposed to blue light grow taller than seedlings exposed to red light after four weeks. Which finding would best support the hypothesis?
- Seedlings in both groups grew during the four weeks.
- Seedlings exposed to blue light had greater average height than those exposed to red light after four weeks.
- Blue lamps used less electricity than red lamps.
- Several seedlings exposed to red light remained healthy.
B directly addresses the prediction. A reports growth without showing which group grew taller. C concerns lamp efficiency. D concerns health rather than comparative height. The exercise stipulates otherwise similar conditions; real experimental interpretation also requires attention to study design and uncertainty.
Worked example: partial support is still partial
A literary critic argues that a narrator both admires a traveller's courage and doubts the traveller's judgement.
A quotation saying “She admired his willingness to cross the pass” addresses admiration but leaves doubt untested. A quotation saying “His courage impressed her, though his decision to leave without supplies seemed reckless” addresses both parts. Match evidence to every essential part of a compound claim.
If the question asks specifically about the critic's claim that the narrator doubts his judgement, the narrower quotation about recklessness could be enough. The stem determines how much of the claim you need to test.
Worked example: evidence against a prediction
A researcher predicts that extending library opening hours will increase evening attendance. After the extension, evening attendance stays approximately the same across comparable weeks.
This finding weakens the predicted increase. “Staff members like the new schedule” is relevant to the policy but does not test attendance. A weakening result does not prove that extended hours could never help elsewhere; keep the conclusion limited to the evidence described.
Source awareness and tempting distractions
A vivid anecdote can illustrate an experience without establishing a general comparison. A quotation can express a character's view without showing the narrator agrees. A statistic can be precise while measuring the wrong outcome. Label whose evidence it is, what it measures, and how it connects to the claim.
When two choices look relevant, finish this sentence for each: “If this finding were true, it would support or weaken the claim because…”. If the explanation needs a fact absent from the prompt, reconsider it.
Review the relationship you missed
An error log should distinguish wrong outcome, missing comparison, wrong speaker, partial evidence, and reversed support. A graph or table question uses the same need for an exact connection, with an additional reading step; see quantitative Command of Evidence.
For conclusions drawn from already supplied evidence, use the inference guide. These neighbouring skills share evidence discipline while asking you to do different work.
Official sources
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