ACT research summaries strategies
ACT Science includes research summary passages across the 40-question, 35-minute section. These passages describe one or more experiments, including the setup, the variables, and the results. Questions test whether you understand the experimental design and can interpret the outcomes. These strategies cover identifying the independent and dependent variables, understanding the experimental setup, and the trap of confusing which variable the researcher controls with which variable the researcher measures.
The core principle
Every experiment has an independent variable and a dependent variable. The independent variable is what the researcher changes or controls. The dependent variable is what the researcher measures. The purpose of the experiment is to determine how the dependent variable responds to changes in the independent variable. If a study tests how temperature affects enzyme activity, temperature is the independent variable (the researcher sets it) and enzyme activity is the dependent variable (the researcher measures it). Controlled variables are everything else kept constant so they do not affect the results. Before answering any question about a research summary passage, identify all three: what the researcher changed, what the researcher measured, and what the researcher held constant.
The most common trap
Confusing the independent variable with the dependent variable
The passage describes an experiment where a scientist grows plants at different light intensities and measures their growth rate. The question asks what the independent variable is. You choose "growth rate" because it is the result. Growth rate is the dependent variable because it is what the scientist measures. Light intensity is the independent variable because it is what the scientist controls. The answer choices include "growth rate" because the test writers know students confuse the cause with the effect. The independent variable is the cause (what the researcher changes), and the dependent variable is the effect (what the researcher measures).
Step-by-step strategy
When to use: any passage that describes one or more experiments, including the setup, procedure, and results.
- 1Skim the passage and identify the independent variable (what the researcher changes), the dependent variable (what the researcher measures), and the controlled variables (what the researcher holds constant).
- 2If the passage describes multiple experiments, note how they differ. Usually each experiment changes the independent variable or tests a different condition.
- 3Read the results table or graph the same way you would for a data representation passage: check the axes, the units, and the trend.
- 4For questions about the experimental setup, return to the procedure section. Do not assume standard lab practice matches what the passage describes.
- 5For questions about modifying the experiment, identify which variable would change and which would stay the same. A valid modification changes only one variable at a time.
When not to use: when the passage presents data without describing an experiment. Use the data representation strategy instead.
Related pages
Research summaries practice questions
Free practice questions with full explanations.
Data representation strategies
Reading axis labels and identifying trends.
Conflicting viewpoints strategies
Understanding each viewpoint before answering.
ACT Science practice
Browse practice questions for every ACT Science topic.
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