知识点 2

Understand procedures and experimental tools described in passages.

Read tools by function. Ask what each step or piece of equipment is doing in the procedure.

核心知识

A procedure question is really a purpose question: connect each tool or step to the specific job it performs in the experiment.

深入理解

ACT Science may mention a probe, bath, filter, indicator, or timing step, then ask what that part of the procedure accomplishes.

  • Measure tools tell you the response variable.
  • Control tools keep a condition steady.
  • Preparation steps make the trial comparable before data are collected.

Do not choose an answer just because the tool sounds scientific. Match it to the exact action described in the passage.

分步讲解

  1. Locate the step: Find where the tool appears in the procedure.
  2. Ask what problem it solves: measurement, control, mixing, separation, timing, or observation.
  3. Check the wording: the best answer usually describes the tool's direct job, not a broad scientific goal.

常见误解

  • Trap: Confusing a control tool with a measuring tool.
  • Trap: Picking an answer that sounds related to the experiment's topic but does not match the step described.
题目

示例解析

Students placed 3 test tubes of starch solution in a warm water bath for 5 minutes, then added amylase to each tube. After 2 minutes, iodine solution was added to check how much starch remained. Why was the water bath used?

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