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Unit 19: Biology Part 2 Page 112 of 137

Activities and Experiments

Lesson 6: Diseases and Defenses

Experiment: How Clean is Clean?

The single best way to prevent the spread of infectious disease is to wash
your hands. But how much do you need to wash them to actually get rid of
all the disease causing pathogens you are carrying? Using a model to

represent pathogen-filled hands, you can find out.

Materials:

 GloGerm, Germ Juice or Glitter Bug

1. Copy a chart like the one below:

0 5 10 15 20
++++

2. Cover your hands with a pathogen simulator, such as GloGerm, Germ
Juice, or Glitter Bug. Cover both your palms and the backs of your
hands, and try to get it on the skin under your fingernails.
3. Look at your hands under a UV light. You will see that the “germs” are
clearly visible. This is time 0, meaning that you have not washed your
hands at all. You will call this level of dirtiness “++++,” or the

dirtiest. This level of dirtiness has already been filled in on the data
table.
4. Wash your hands for five seconds. Again look at your hands under the
UV light. Rate their dirtiness as either ++++, +++, ++, +, or –,
where ++++ represents as dirty as they were at the start, and –
represents totally clean.
5. Wash your hands for an additional 5 seconds, and record their
cleanliness after 10, 15, and 20 seconds total.

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