Wash your hands! (continued)
+
ward
'
s
science
5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com
Find materials for this activity at wardsci.com.
Discover more free activities at wardsworld.wardsci.com
Expected Results:
Results may vary based on materials used, setup, procedure, and other factors, however, here are a few examples on what to expect:
• The bread from the group that thoroughly washed their hands with soap and water should have the least growth.
• The bread from the group that handled the bread without washing their hands at all will have the most growth.
• The gloved hands and hands washed with sanitizer will have an intermediate amount of growth.
Note, unless your gloves are sterile, you will likely still see growth. Depending on the type of glove (latex, nitrile, vinyl) and how long the
box of gloves has been open and exposed to the elements, you may see more or less growth.
Follow-up Teaching Notes:
• If you don't see growth beginning on the un-washed bare hand sample after about 5 days, it may be too cool and/or dry in
your classroom. Mold grows best in dark, warm, humid temperatures. Approx. 70–80°F is ideal (21–27°C). Add a few drops of
water to each bag.
Add Inquiry:
• What happens if you leave a piece of bread on a table, un-disturbed for 30 minutes, and then transfer it to a plastic bag?
How does the growth compare to that on a piece left in the hallway while students pass between classes in the hallway?
• Compare the growth on a piece of bread handled by one person vs. one handled by the entire class.
• What happens if you just rinse your hands with water? What about only washing your finger-tips? What if you shorten the
length of time you scrub your hands with soap?
• Will you see a difference in the mold growth if you add more/less water? What about if you put the baggies in the dark
vs. the light?
• Does the presence or absence of preservatives in the bread affect the growth rate of the mold?
Disposal/Clean-up:
• Discard the bread in the trash.
• Wash your hands after handling the bags.
