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Measuring problem

Postby Em2333 » Sun Dec 06, 2015 8:40 am

I am doing my science fair project using the glo germ kit. I am testing different soaps to find out which one is the best at removing germs from hands. My variable is the different soaps (antibacterial vs. no antibacterial, and hand sanitizer (70% ethyl alcohol vs. non alcohol based). My problem when taking the pictures of my hands after using all the different soaps is how to measure the germs in order to make a graph and table. Should I do percentage of hand germ free or covered or how can I truly get this to be a measurable so I can compare the soaps and graph it. Also, after using one soap, should I go and touch the same object each time or not worry about that. Please help and offer some advice. Frustrated parent trying to help her fourth grader. Thank you for any advice you can give me to make this project work!!!

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Re: Measuring problem

Postby trystanloustau » Sun Dec 06, 2015 6:00 pm

Hi, Em! This sounds like a cool project! Although it may seem tricky trying to convert qualitative data, like the visual glowing germs in this experiment, into quantitative data, the "numbers" needed in order to graph, it is a lot easier than you may think. If you followed the procedures listed on the Science Buddies page for this project, make sure you keep track of which participants in each row of the data table correspond to each type of soap together. Then, simply add the number of check marks for each ROW. The number of check marks will be the numerator of a fraction whose denominator is 5, since there are 5 sections of the hand being checked for germs. This fraction, when converted to a percentage (after multiplying both the numerator and the denominator by 20, the numerator will be the percentage), will represent the amount of the hand that still contains germs. After doing this for every participant, you should average the percentages for each soap by adding all the percentages and dividing by the total number of percentages for each soap.

Then, you should make a bar graph to show your results. You use a bar graph because you are trying to find out which soap is the best, and bar graphs are excellent tools for comparison of this type. Your x-axis will be your independent variable (the type of soap). Your y-axis will be your dependent variable (the percentage of the hand still covered in germs). The best soap will be the one with the lowest percentage, or the shortest bar. If you have any other questions, feel free to ask.

Good luck! —Trystan

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