知识点 4

Recognize assumptions and limitations in claims and models.

A strong-sounding claim can still rest on a narrow or weak design.

核心知识

A claim is only as strong as the design behind it. If the method leaves out a control, uses a narrow sample, or changes two things at once, the conclusion has to stay narrow too.

深入理解

ACT Science often hides the weak point in a confident-sounding claim.

  • Assumption: something the claim quietly treats as true without testing it directly.
  • Limitation: something about the method or sample that restricts how far the result can reach.
  • What to check: sample size, uncontrolled variables, measurement method, and whether lab conditions stand in for real conditions.

A confident tone does not erase a weak design.

分步讲解

  1. Ask what had to be true for the claim to work.
  2. Check whether another variable could also explain the result.
  3. Look for narrow samples, missing controls, or mismatches between the tested setting and the claimed setting.

常见误解

  • Treating a clear pattern as proof that the design had no limitation.
  • Assuming a greenhouse or lab result automatically applies to outdoor systems.
  • Overlooking that two variables changed together, so the study cannot isolate either one cleanly.
题目

示例解析

Researchers compared treated and untreated tomato plants in a greenhouse for one growing cycle and found higher mean fruit yield in the treated tomato plants. To conclude that the fertilizer will increase fruit yield for all crop species in outdoor farms, the researchers must assume that:

选择一个答案查看解析