Science Fair project questions. Good project idea? If so, what is my Independent Variable?

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Lancasterchallenge
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Science Fair project questions. Good project idea? If so, what is my Independent Variable?

Post by Lancasterchallenge »

Do you think this is a good idea for a Science Fair project?
"Which has more bacteria on it in restaurants; menus or the entrance handle to the bathroom?"

Our controls would be swabbing a brand new (right out of the box) handle, and a new printed menu.

The dependent variables would be four samples swabbed from menus and bathroom handles at four different restaurants.

Another question is what is my independent variable supposed to be? The judge's form states, "Did the student have one and only one independent variable?" Would my independent variable be the different restaurants? Or is it the actual swabbing and testing in the same Petri dishes (Agar plates)?
Thanks so much!
Heidi
koneill18
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Re: Science Fair project questions. Good project idea? If so, what is my Independent Variable?

Post by koneill18 »

Hello,

This sounds like a cool project idea! Your independent variable is the thing you're controlling in the experiment and the dependent variable is the output that you're measuring. In this case, the thing that you have control over is the locations that you're swabbing to sample for bacteria. So that would be your independent variable. The dependent variable is the thing you are measuring, which would be the amount of bacterial growth in each location. If you're looking for a negative control for your experiment, you could just use a plain unused swab instead of a new handle or menu. Those things could have bacteria on them since people likely touched them at some point. A swab on the other hand is designed to be sterile. If run an unused swab across a petri dish and you see bacteria growing on that plate, it's a good indicator that your plate is contaminated and those results aren't trustworthy.

I hope this helps! Let us know if you have more questions or need more clarification.
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