Ready to learn more? Go through Mr. Jones’ interactive activity:
Understanding Scientific Variables and Controls
Introduction to Terms
In this activity, you’ll learn about key scientific concepts such as manipulated variables, responding variables, controls, and control groups. Click through each section to understand these terms before viewing examples.
Manipulated vs. Responding Variables
Manipulated Variable (Independent Variable): The variable that is changed or controlled in an experiment. For example, in an experiment testing how different amounts of sunlight affect plant growth, the amount of sunlight is the manipulated variable.
Responding Variable (Dependent Variable): The variable that is measured or observed in an experiment. In the plant growth example, the height of the plants is the responding variable.
Controls in an Experiment
Controls: These are the factors that are kept constant throughout the experiment to ensure that the results are due to the manipulated variable alone. For example, in the plant experiment, the type of soil, water amount, and temperature should be kept the same for all plants.
Control Group vs. Controls
Control Group: A group in an experiment that does not receive the experimental treatment and is used as a benchmark to compare against the manipulated group. For instance, if you’re testing the effect of fertilizer on plant growth, a control group would be plants that receive no fertilizer.
Controls within the Experiment: These are the variables that are kept constant in both the experimental and control groups to ensure a fair test.
Examples
Example 1: Plant Growth Experiment
Scenario: Testing how different amounts of water affect plant growth.
Manipulated Variable: The amount of water given to the plants.
Responding Variable: The height of the plants.
Controls: Type of plant, type of soil, amount of sunlight, and temperature.
Control Group: Plants that receive no additional water (baseline for comparison).
Example 2: Fertilizer Impact on Plants
Scenario: Testing how different types of fertilizer affect plant growth.
Manipulated Variable: The type of fertilizer used.
Responding Variable: The growth rate of the plants.
Controls: Amount of water, type of soil, light conditions, and temperature.
Control Group: Plants that receive no fertilizer (baseline for comparison).
Example 3: Temperature Effects on Reaction Time
Scenario: Measuring how different temperatures affect reaction time.
Manipulated Variable: The temperature at which the reaction time is measured.
Responding Variable: The time it takes for a reaction to occur.
Controls: Type of reaction, environment, and the method of measurement.
Control Group: Reaction time measured at room temperature (baseline for comparison).
Example 4: Light Exposure on Plant Health
Scenario: Examining how different light conditions affect plant health.
Manipulated Variable: The amount of light exposure.
Responding Variable: The overall health of the plants.
Controls: Type of plant, type of soil, amount of water, and temperature.
Control Group: Plants that receive no light (baseline for comparison).
Example 5: Effect of Music on Study Performance
Scenario: Testing how listening to different types of music affects study performance.
Manipulated Variable: The type of music played while studying.
Responding Variable: The performance on a test or quiz after studying.
Controls: Study materials, amount of study time, and the test or quiz itself.
Control Group: Participants who study in silence (baseline for comparison).