1. Laboratory Experiment
Soap vs. Sanitizer
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Laboratory Experiment

2. Why wash your hands?
Hand are the most frequent transmission route for many types of infections.
Pathogens may enter through the mouth, nose, or eyes.
Proper hand hygiene is the easiest way to reduce infections.
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3. How do you wash properly?
Scrub your hands with soap and warm water for 20 seconds to 2 minutes.
Scrubbing your hands physically removes dirt and grease, which wash away with the water
Bacteria can attach to dirt and grease particles on your hands, so removing these reduces places of colonization.
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4. What about hand sanitizer?
When water is not available, hand sanitizer can be an effective alternative.
The alcohol in hand sanitizer disrupts the coating on bacteria and viruses.
Use enough sanitizer to keep your hands wet while you rub for at least 30 seconds.
Alcohol denatures proteins.
A person who uses hand sanitizer is likely to show slower redevelopment of bacteria.
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The use of hand sanitizer in school is also relatable to a drop in illness rates and better records.

5. Soap vs. Sanitizer Experiment
Problem/Question:
Which is more effective at reducing the amount of bacteria on hands: washing with soap or antibacterial sanitizer?
Hypothesis & Prediction:
If washing with soap and water is more effective at reducing the amount of bacteria on hands, then the soap treatment will show a greater reduction in bacterial growth than the sanitizer treatment.
Have students fill in this information on their pre-lab write-up form.
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6. Experimental Design Independent/Manipulated Variable:
Cleanser/Chemical
Dependent/Responding Variable:
Bacterial growth
Treatments:
Soap
Sanitizer
Control:
No soap or sanitizer
Analysis:
Compare percent reduction in bacterial growth
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7. Methods Label your Petri dish Group #Treatment Before/After Control

8. Methods
How to sample:

9. Methods Apply treatment for 30 seconds
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10. Number of Bacterial Colonies
Analysis
# Before - # After = Difference
Difference ÷ # Before = Reduction
Reduction x 100 = % Reduction
TREATMENT
Number of Bacterial Colonies
Before
After
Difference
% Reduction
Control 1
Control 2
Control Average:
Soap 1
Soap 2
Soap Average:
Sanitizer 1
Sanitizer 2
Sanitizer Average:

11. Number of Bacterial Colonies
Analysis
Sample results:
TREATMENT
Number of Bacterial Colonies
Before
After
Difference
% Reduction
Control 1
119
500
-381
-320%
Control 2
198 32
166
83.8%
Control Average:
-118%
Soap 1
100 68
32%
Soap 2 6 90
-84
-1400%
Soap Average:
-684%
Sanitizer 1 7 1
85.7%
Sanitizer 2 23 2 21
91.3%
Sanitizer Average:
88.5%
Should be ≈ 0
Should be > 0