The tip
In every experiment passage, ask two questions first: what did the researcher change on purpose (independent variable), and what did they measure (dependent variable)? Many questions are just this in disguise.
Try it
A student grows identical bean plants in the same soil and sunlight. Each plant gets a different amount of fertilizer, and the student measures each plant's height after 3 weeks. Which is the independent variable?
- APlant height
- BAmount of fertilizer
- CType of soil
- DAmount of sunlight
Reveal answer
Answer: B. Amount of fertilizer
The student chose a different amount of fertilizer for each plant, so fertilizer is the independent variable. Plant height is what was measured (dependent). Soil and sunlight were kept the same, so they are controlled variables.
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