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STEM Fair Tutorial #13: Lights...Camera...Action

It's time to start a journey into creating a STEM Fair experiment; but before we do - we think it's time to review the script.

We would like for you to imagine, for brief moment, that your STEM Fair experiment is similar to a play or a movie in the theater. In a play or movie, every character, every piece of scenery, every score of music that is played has a specific role and purpose and that is to provide the viewer with insight and a greater understanding of the story. A STEM Fair Experiment is very similar to a play - only you are the director, the actors are the materials, the script is your research, the action notes are your procedures and the final production is your STEM Fair Display and presentation. Every piece of your experiment plays a valuable role and one of the most important role is that of "The Variable."

What exactly is a Variable?

That is an excellent question! And since this is a website that works with Science, Technology, Engineering and Math - we'll talk about what a variable is in each of these areas; however, for this posting series on STEM Fair experiment - the variables we'll discuss and most likely use will fall under the Scientific definition of a variable.

Variables in Science:

In Science, the word: Variable means something that you can either change, something that you can control or something that you can measure. There are three main types of variables that you may use in a science experiment and they are the:

The Independent Variable

The Dependent Variable

The Control Variable.

Let's review each in more detail.

1. Independent Variable

a. Definition of an Independent Variable: In your science experiment, this is something that you change.

b. Example of an Independent Variable: If you are studying the effects of water amounts on the growth of plants you may choose to change the amount of water you give to a each plant.

c. The role of the Independent Variable: When conducting a Science Experiment you change ONLY ONE Independent Variable at a time. There is a very specific and simple reason for this action - you want to learn the impact of one change at a time. Imagine for a moment if you were studying the effect of water amounts on the growth of plants and then you decided to change the amount of sunlight the plants received. By change two factors at the same time - you would not be able to learn the impact or effect of either. So remember the Independent Variable likes to stand alone and it is very Independent - it doesn't like to share the spotlight with other Independent Variables.

2. Dependent Variable

a. Definition of a Dependent Variable: The dependent variable is the reaction to the use of the Independent Variable.

b. Example of a Dependent Variable: Using the example of studying the effects of water amounts on the growth of the plants; the Dependent Variable is how the plants react to the amounts of water. For example, did the plants grow faster or slower depending upon the amount of water given.

c. The role of the Dependent Variable: The Dependent Variable provides you with valuable clues that help you learn exactly what is the perfect amount of water for the plant you are researching.

3. Control Variable

a. Definition of Control Variable:A control variable is something that remains the same and does not change at all during your experiment.

b. Examples of Control Variables: Utilizing the same experiment above some of the Control Variables should be: The type of plant, soil and light exposure. Remember if your experiment is studying the effects of water amounts on a plant then the ONLY THING YOU CAN CHANGE IS THE AMOUNT OF WATER. Everything else must remain "controlled" and the same. If you begin changing other factors then you will not know whether the plant changed because of the amount of water or soil or daylight. Only change one factor per experiment.

c. The role of the Control Variable: Every play or movie has to have something that is steady and reliable; the same applies to a STEM Fair experiment. If you begin changing too many things you create chaos and confusion.

There are additional types of Independent and Dependent variables that we will discuss in the next post. Today, we really want you to understand these three types of variables and the roles they play with in your STEM Fair experiment.

Homework and Materials:


Composition Notebook and Pen


Tonight we want you to focus on learning more about the three types of variables: Independent, Dependent and Control. Taking into consideration your Problem, Question and Hypothesis - What do you think the Independent, Dependent and Control Variables could be?

Entry #12: In your lab notebook write down the three variables you would need to incorporate into your STEM Fair experiment.

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