Experiment: Soapy Solutions
For all student levels; time: 1-2 hours
(Students working on their own, might want to check out a "Just for Kids" version
of Soapy Solutions,
also on this website.
When was the last time you washed your hands? Did you use soap? What
have you done since you washed? Have you eaten, put your fingers in your
mouth, or touched someone else?
Observations in public restrooms have revealed that only about 68 percent
of Americans wash up before leaving. Yet thorough hand washing is one
of the best ways to prevent the spread of infections. There are millions
of microbes on your hands. Most are naturally occurring and harmless,
but some may be disease-causing germs. Hand washing with soap lifts off
those microbes and rinses them away. Hand washing with plain soaps or
detergents suspends microorganisms and allows them to be rinsed off.
Anti-bacterial soaps may potentially kill off harmless bacteria and may
ultimately lead to the development and proliferation of resistant microorganisms.
Have students conduct an experiment to discover what is the most effective
way to remove bacteria from your hands.
Cooking oil, cinnamon, access to sink to wash
hands, and measuring spoons. Ask 3 students to volunteer for the
|| For the student
|| Rub 1 tablespoon of cooking oil all over your hands
until completely coated. Sprinkle 1 teaspoon of cinnamon on hands
and rub it around until it's evenly distributed. The cinnamon will
be like bacteria. It's all over!
|| Wash hands as follows, rubbing them briskly for 20
Student #1: wash hands with cold water and no soap.
Student #2: wash hands with warm water and no soap.
Student #3: wash hands with warm water and soap.
|| For added variety, compare above methods by varying
the time for rubbing hands, i.e., 5 seconds, 10 seconds, and 20 seconds.
For simplicity, you may want to try this with 3 students washing
hands with warm water and soap, method #3.
|| For the rest of
|| Develop a hypothesis.
|| Observe the 3 hand-washing methods.
|| Record the results, looking for the amount of cinnamon
(bacteria) that remains after the various washing methods. The method
of hand washing that removed the most "bacteria" was .... The method
that removed the least "bacteria" was ....
|| Illustrate how the hands of students 1, 2, and 3
looked after washing.
|| Draw conclusions.
I can remove bacteria from my hand by ....
If I used only cold water and no soap to wash, this is what might
Why does the warm water help? Soap? Rubbing?
How long does it take to get the bacteria washed off?
| 1. How might hand washing
affect your family's health?
You can spread germs to anyone or anything in your home that you
touch. You can also get germs from objects other people have touched.
If members of your family make an effort to wash often at appropriate
times, you can help reduce the chances of each other getting ill.
2. What difference does soap make?
As the experiment showed, washing with water alone doesn't do as
good a job as washing with soap. In the same way the soap lifts off
the cinnamon so it can be rinsed away, soap grabs microbes so they're
flushed away by the water. You just can't see it happen as easily
with invisible microbes as you can with cinnamon.
3. What difference does the water temperature
make? Warm water facilitates the soaping action on the
hands so that it can more easily lift off the cinnamon "bacteria." It
does not kill the bacteria, but makes it easier for the germs to
be washed away with the vigorous rubbing of hands and fingers.
4. What infectious diseases could be spread
by failure of people to adequately wash their hands?
There are many germs that can be spread or picked up through inadequate
hand washing. For example, cold viruses can be spread by touching
people or objects. The flu virus is often spread by contact with
infected people. Salmonella, a bacterium that causes severe upset
stomach, can be picked up from surfaces where raw foods--particularly
meats--have been sitting. That's why hand washing not only protects
you from illness, but also helps protect all those people you come
into contact with.
|Source: The Partnership for Food Safety
Education, a unique public-private coalition of industry, government,
and consumer groups created to reduce the incidence of food-borne
illness by educating Americans about safe food handling practices.
Fun with Fomites
Banner microbe: Adenovirus (virus causing
from the American
Museum of Natural History Epidemic! exhibition
Teacher's Guide | Epidemic! | Exhibits