Please remove your shoes. It's a standard rule in many homes, but some people don't really think much of it, wearing shoes around the house and even allowing them to touch surfaces like chairs and beds. The potential effects of this is more shocking than people realize and you'll be able to show this with the results of your science fair project.
You should test a variety shoes to get the most results. For example, you might test bacteria levels on a brand new pair of shoes, as well as the same shoes worn for a few weeks. Add to the mix your oldest, stinkiest pair of sneakers, the flip -flops you wear to the beach and the shoes you wear to the dog park. All of these shoes are likely to show some bacteria growth, with the dirtier shoes showing more bacteria. Perhaps the most surprising to people, though, is that even shoes that look clean or that have been cleaned can still have some bacteria on them.
Interpreting Your Results
According to Home Science Tools, a company that sells science equipment, you should see bacteria growth in your petri dishes within three to seven days. Large clumps of "dots" represent larger amounts of bacteria. If there's more than one color or texture growing, it means that there were multiple types of bacteria present on the shoe's sample.
Presenting the Results
Visual elements are the key to making this a successful science fair project. Those who view your exhibit should be able to clearly see the amount of bacteria present on the shoes. One way to do this is to pair up a picture of the shoe with a picture of the petri dish showing the results. You might also show the actual shoes and samples. If you want to make your display more interactive, bring along a stereo microscope to allow people to see the bacteria growth up close. Another idea is to have visitors guess how much bacteria was present on different types of shoes, creating "trick" answers, like "none" for a brand new shoe.
Making the Results Meaningful
The take-home message of this experiment is that even the cleanest pair of shoes has bacteria on the bottom and if people are wearing shoes in the home, they are tracking these germs all over the house. Even if the wearer removes her shoes in a mudroom, if she steps in the same area with bare or stockinged feet she may track bacteria around the house.
- Photo Credit Jupiterimages/BananaStock/Getty Images