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The Five Second Rule!

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by

Peter Barnes

on 10 February 2017

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Transcript of The Five Second Rule!

If you pick up food that has dropped on the floor within five seconds, is there less bacteria present than if the food is on the ground longer?
Preparing the Petri Dishes!
First, you will boil the agar in a pot of water. Next, you will pour the agar into 14 Petri dishes and leave them to sit in the fridge overnight. The agar will harden into a gelatin-like substance.
My Hypothesis:
I believe that the food will have more bacteria on it the longer it is on the ground because the food will have more time or exposure to the bacteria.

I also predict that the wet food (bologna) will attract more bacteria.

Finally, I think that food dropped on the wood floor will have more bacteria present compared to food dropped on the carpet.
Question:
Materials:
Q-tips
Bologna
Bread
A timer
Rubber gloves
Petri dishes
Agar
Independent Variables:
One independent variable will be the type of floor. Will the type of floor the food is dropped on influence the results? carpet vs. wood

Another thing I will be changing is the food type. For example, I will drop a wet food (bologna) as well as a dry food (bread).

Finally, I will adjust the times that the food is in contact with the ground (0 seconds, 2 seconds, 5 seconds, and 10 seconds)
Controls:
slice of bread
bologna
I will drop the food in the same location and at the same time intervals
the method will be the same.
The Five Second Rule

By: Rio Hall
Dependent Variable:
I will measure the amount of germs/dirt/bacteria on the slice of bread or bologna by swabbing each item with a sterile swab and wiping the swab on individually labeled Petri dishes and counting the bacterial colonies after 3 days of incubation.
5 Second Drop
You will now drop another piece of bologna on the ground and leave it there for 5 seconds. You will swab a different Q-tip on the new piece of bologna all over it. You will then rub the Q-tip on the agar solution in the Petri dish.
Since my experiment did not answer my question about the validity of the 5 Second Rule, I searched to find answers.

In one study conducted by Professor Donald Schaffner of Rutgers University, it was determined that even if you pick up food dropped on the floor quickly (under 5 seconds), you will absolutely pick up bacteria with it.
Some Other People's Results
One person discovered that lots of bacteria can transfer onto the food with 5 seconds. They proved this by showing different pictures of the bacteria inside the petri dish. Many other people came to this final result as well.
What Were Some Mistakes That I Made?
Clearly, my method was flawed. One mistake I made was that I didn't turn the Petri dishes upside-down during the incubation period (when I was waiting for the bacteria to grow.) This caused condensation to form inside the dishes. Because of the condensation, all of this water formed a puddle on top of the agar so that no bacteria could grow.
Once you have done that, you will get out the bologna and swab it with your first Q-tip without dropping it on the floor. This will serve as the control. You will then rub the tip of the Q-tip gently on the gelatin agar in the Petri dish.
No Drop
2 Second Drop
The next step is to drop a second piece of bologna on the ground and leave it there for 2 seconds. After that, you rub the next Q-tip across the side of the bologna that was against the floor. Finally, transfer the sample by wiping the Q-tip all over the agar in a carefully labeled Petri dish.
10 Second Drop
Finally, you will drop the bologna on the ground and let it sit there for 10 seconds. Pick it up and rub the last Q-tip across the bologna. Finally, swab the same Q-tip on the last petri dish. Repeat all of these steps for the bread. Be sure to test both food items on the wood floor and the carpet at the same time intervals.
These are the Petri dishes I prepared!
This is the bologna that I dropped on the hard floor.
This is me swabbing the Q-tip on the agar.
This is the piece of bologna that was dropped on the ground for 5 seconds
This is one of the pieces of bead that I dropped.
The End!
This is a picture showing one of the Petri dishes that did not grow any bacteria.
Unfortunately, my 5 second rule experiment went terribly wrong! When I went to count the bacteria colonies in my Petri dishes, THERE WERE NONE!!!!!!!!!!!!!!!!!!!
Even though my experiment failed, my hypothesis was correct. Schaffner's study found that carpet had a very low rate of bacteria transmission compared to hard floors.

The second part of my hypothesis was also proved to be true by his study. It proved that wet foods (bologna in my study) absorbed more bacteria than dry foods (bread in my study.
I learned two valuable lessons from my 5 Second Rule Experiment:

1. Even though my experiment did not go the way I planned, I still learned something. Science experiments are often about trial and error.

2. Do NOT eat any food that falls on the floor, even for a second!
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