Testable Questions

Testable Questions

Middle School

​

Learning Objectives

• Define a testable question and identify its key characteristics.

• Differentiate between independent, dependent, and control variables.

• Formulate a testable question using standard formats.

• Distinguish between a control group and an experimental group.

Key Vocabulary

​

Testable Question

A question that can be answered by designing and conducting a scientific experiment.

​

Independent Variable

The one factor that a scientist chooses to change on purpose during an experiment.

​

Dependent Variable

The factor that is measured or observed to see how it is affected by the change.

​

Control Variable

A factor that is kept the same throughout an experiment to ensure fairness and reliability.

​

Control Group

The group in an experiment that does not receive the new experimental treatment.

​

​

What is a Testable Question?

Good Scientific Questions

• ​Can be answered through direct observation or measurement in an experiment.

• ​​Focuses on changing one thing to see its effect on another thing.

• ​They are specific and can be proven using evidence from an investigation.

Bad Scientific Questions

• ​Are often based on personal opinions or feelings rather than facts.

• ​​Use vague words that mean different things to different people.

• ​Cannot be proven true or false through an experiment or test.

Multiple Choice

Which of the following is a key characteristic of a good scientific question?

• It asks for a procedure, like 'how to bake a cake'.

• It is based on personal opinions.

• It uses words that mean different things to different people.

• It can be answered by direct observation or measurement.

​

​

Variables in a Testable Question

• The independent variable is what a scientist intentionally changes or manipulates.

• The dependent variable is what is measured or observed to see the effect.

• Think of the independent variable as the cause and the dependent as the effect.

• Questions ask: How does changing the (Independent Variable) affect the (Dependent Variable)?

Multiple Choice

In the question, 'How will the weight of a paper airplane affect the distance it travels?', what is the independent variable?

• The color of the paper.

• The distance the airplane travels.

• The person throwing the airplane.

• The weight of the paper airplane.

​

​

What Are Controls in an Experiment?

• A control group does not receive the experimental treatment being tested.

• An experimental group is the group that receives the treatment.

• The control group is a baseline to compare the results against.

• Note: Control variables are factors kept the same for a fair test.

Multiple Choice

In an experiment testing if adding salt to water changes its freezing time, what would be a necessary constant variable?

• The brand of salt used.

• The amount of salt added.

• The amount of water in each sample.

• The time it takes for the water to freeze.

​

Common Misconceptions

Misconception	Correction
Any question can be tested in an experiment.	Only testable questions can be answered by measurement or observation.
You can change multiple things at once in an experiment.	A fair test changes only one variable at a time.
A research question is the same as a testable question.	A testable question requires an experiment; a research question does not.

Multiple Choice

A student wants to test the question: 'Does the type of music played affect a plant's growth height?' What is the best way to set up a control group for this experiment?

• Ask a friend which music they think is best for plants.

• Measure the height of the plant before playing music.

• Play different types of music for the same plant.

• Have one plant grow with no music playing.

Multiple Choice

Based on the standard format for scientific questions, which of the following is the best-written testable question?

• How does a cat's diet affect the number of hairballs it produces?

• How do you take care of a cat?

• Why do cats purr?

• Are cats or dogs better pets?

Multiple Choice

A scientist is testing how the density of different liquids (water, oil, syrup) affects how fast a marble sinks. To ensure a fair test, what important factors must be kept constant for all trials?

• The location of the experiment and the type of liquid.

• The time it takes for the marble to sink in each liquid.

• The type of liquid and the size of the marble.

• The size, shape, and mass of the marble, and the drop height.

Multiple Choice

Analyze the hypothesis: 'If I drink Mountain Dew before bed, then I will not sleep very much.' What are the independent and dependent variables in this scenario?

• IV: Amount of sleep; DV: Drinking Mountain Dew.

• IV: The bed; DV: The person sleeping.

• IV: The time of day; DV: The brand of soda.

• IV: Drinking Mountain Dew; DV: Amount of sleep.

​

Summary

• A testable question compares an independent variable to a dependent variable.

• Good scientific questions are specific, measurable, and can be tested with evidence.

• The independent variable is changed, while the dependent variable is measured.

• Use constants and a control group to ensure the experiment is fair.

Poll

On a scale of 1-4, how confident are you about formulating your own testable question?

• 1

• 2

• 3

• 4