Identify hypotheses, independent/dependent variables, and control conditions.
Name each part by its job. Do not guess from whatever number looks most important.
核心知识
The independent variable is changed on purpose, the dependent variable is measured, and the control condition is the baseline comparison.
深入理解
Students often miss these questions because they label the most noticeable number as the independent variable.
- Change: What did the researchers deliberately vary?
- Measure: What outcome did they record?
- Control: Which condition serves as the baseline for comparison?
If the passage states a hypothesis, match it to the same map. A hypothesis usually predicts how a change in one factor will affect a measured result.
分步讲解
- Find the test factor: Look for the condition that changes across groups or trials.
- Find the measured result: Look for what was recorded at the end, during the trial, or after treatment.
- Find the baseline: Look for the untreated, standard, or zero-change condition used for comparison.
常见误解
- Trap: Calling a constant condition the independent variable just because it is mentioned in the setup.
- Trap: Treating time or sample size as the dependent variable when the passage actually measures a biological or chemical result.
示例解析
In an experiment, students tested whether fertilizer amount affected bean plant height. Each plant received the same soil, pot size, and amount of light. The plants were given 0 mL, 5 mL, or 10 mL of fertilizer per week, and height was measured after 3 weeks. Which statement correctly identifies the variables and control condition?
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