How to Succeed at a Science Fair: Design Good Experiments.
I have a Hypothesis, Now What?
Your Observations about an interesting phenomenon have provided you with the Question that needs to be addressed. Your Hypothesis and Prediction(s) will provide you with a framework to Design your Experiments so that you can start collecting your Results. When designing your experiments, there are two key factors to consider, Independent Variables and appropriate Controls.
What is an Independent Variable?
Independent Variables are scenarios devised by you, the scientist; the variables that you control. This is to be distinguished from the Dependent Variable, the variable that is controlled by the Independent Variable, in other words, the Results. It is also distinguished from variables that you are not controlling but that can also affect your results and skew the data away from the true answer. We will talk about this later.
Science Insight
Did you know that the independent variable is plotted on the X-axis of a graph while the dependent variable is plotted on the Y-axis? For more advice on expressing your data, CONTACT ME, your Microbe Mentor..
Free 15-minute consultation available.Case Study 1: Examples of Independent and Dependent Variables in an Experiment
In an experiment that addresses how long it takes a beetle larvae to pupate (form a cocoon) at different environmental temperatures, an example of an independent variable would be a given temperature. The corresponding dependent variable would be how long it takes the larvae to develop into pupae at that temperature. One cannot know what the dependent variable will be until the data presents that answer!
Case Study 2: BE FAIR! Are all the Other Variables the Same for each Independent Variable? The Importance of Controls.
Let us say that you are examining how long it takes larvae to pupate over a range of temperatures (0 degrees Celsius to 50 degrees Celsius). Can you demonstrate that all the other variables that are not being evaluated are the same at each of these temperatures?
Firstly, we will assume that all the larvae are the same age, as they should be. But, are the light intensity, the oxygen levels, the humidity levels, etc. the same at each temperature? This is where controls are applied. Meters that measure these environmental variables could confirm that all the untested variables are the same.
What if you find that the incubator is more humid at 50 degrees Celsius than at the lower temperatures? Then you will have to somehow ensure that the humidity of all the other incubators is the same as at 50 degrees or the data may be skewed if it happens that humidity also affects the time that it takes beetle larvae to pupate.
