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STEM Fair Tutorial #11: Pose a Question

After identifying a problem and conducting some background research – you will then form a question that will help you to begin developing your hypothesis and your experiment plan. While this may appear simple, it is extremely easy to create a question that is either too broad or specific for experiments.

Thankfully, the Monroe Career & Technical Institute in Bartonsville, PA created a fantastic presentation to assist you with this topic. Since we like to work smarter not harder - we provided a link to their presentation. However, if you are unable to download the document - we opted to recreate the content in this blog post and it is provided below for your review. Well done Monroe Career & Technical Institute!

What is a "Testable Question?"

Testable questions are always about changing one thing to see what the effect is on another thing.

For Example: Does changing the height of the ramp affect the speed of a car going down the ramp?

Here are some fill in the blank Testable Question Formats to assist you in developing your own STEM Fair Experiment Question:

1. Does changing __________ affect _________?

2. How does changing __________ affect _________?

3. If I change __________,will it affect _________?

In a scientific experiment, these two blank sections have special names called: variables. We will discuss variables in tomorrow's blog post; however, for now here is some basic information to familiarize you with what variables are and their importance in developing a STEM Fair experiment question.

What is a variable?

A variable is something that can CHANGE and Testable Questions have two variables in the statement. The first is the Independent Variable and the second is the Dependent Variable. The Independent Variable is the cause and the dependent variable is the effect or outcome.

What is an Independent Variable?

The Independent Variable is the variable that will be changed by you –the scientist. A good experiment has only one independent variable!

What is a Dependent Variable?

The variable that is being measured in your experiment. The dependent variable is the response to the change you make using the independent variable.

Using the Testable Question Formats from above - let's insert the location of the Independent and Dependent Variables.

1. Does changing Independent Variable affect the Dependent Variable?

2. How does changing Independent Variable affect Dependent Variable?

3. If I change Independent Variable will it affect Dependent Variable?

Here is an example of an experiment question:

Does changing the height of the ramp affect the speed of the car going down the ramp?

What is the independent variable and what is the dependent variable for the question above?

The independent variable is, "the height of the ramp."

The dependent variable is, "the speed of the car going down the ramp."

Another Testable Question

Does changing the amount of light affect the growth rate of plants?

Identify the INDEPENDENT variable

Identify the DEPENDENT variable

Is this a Testable Question?

What makes plants grow best?

It can be a testable question- however, right now the questions is too broad. So, let's turn it into a testable question.

How to Turn a General Question into a Testable Question

First, read the question carefully. What makes plants grow best? Next, think of a cause and an effect related to your question. What makes plants grow best? In this case, the idea is that you can change something to affect something about how a plant grows.

What are examples of things you can change?

a. You can change the amount of water you give to a plant.

b. You can change the amount of sunlight you give to a plant.

c. You can change the type of soil you give to a plant.

What are examples of specific effects can you look for in this experiment?

a. The height of plant.

b. The speed of growth of the plant.

Now that you know the things you can change (independent variable: water, light, soil); insert the cause and the effect (dependent variable: height, speed of growth) into the question format:

“What is the effect of _______________ on _________________?

The cause goes in the first blank, and the effect goes in the second blank. So a testable question looks like this:

“What is the effect of soil type on plant height?

Controls are all the factors in your experiment that you want to remain constant. For example, the Controls for the plant experiment are:

a. The type of plant.

b. The growing conditions (sunlight, temperature, etc.)

c. The amount of water.

d. The type of container.

Here’s another example...Is it Testable?

How does a paper airplane fly? Is this a testable question? Well, almost, so let’s make it into a testable question. Decide what you are going to change (independent variable). For example are you going to change:

a. The size of the plane?

b. The style of the plane?

c. The type of paper used to make the plane?

Now decide what you are going to measure (dependent variable):

a. Distance the plane will fly.

b. The Length of time the plane stays in the air.

Now make the Question testable by selecting one independent variable and one dependent variable. Put them together to create the testable question:

“How does the type of paper affect the distance a paper airplane flies?"

What are the controls that could be used for this experiment? The Controls are:

a. The style of airplane.

b. The Flying conditions (wind).

c. How you throw the airplane.

Final Thoughts

a. Keep your experiment simple and clear.

b. Check out the library or web links for ideas.

c. Don’t wait! Some projects take time to do.

Homework and Materials:


Composition lab notebook and pen.


Entry #10: Based on the problem you researched - what question do you think needs to be answered. Utilizing the information in this post - create a possible question for you to research.

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