Senses and ScienceAbility: The Invisible World Around Us

In this laboratory experience, participants started with observations of the macroscopic world of a piece of tree trunk and plant. Then they looked at the microscopic cells of the plant and the chloroplasts inside the cells. From there, they looked at the world that is all around us: small, multicellular animals, microscopic plants and animals, bacteria, fungi, and parasites. Participants explored the importance of hand hygiene. Each participant placed a finger onto one half of a numbered plate of culture medium, used foam disinfectant, then placed their disinfected finger on the other half of the medium. The following data table and pictures show the "before and after" results.

Out of 39 samples, there was clear improvement on 33 samples after disinfection with alcohol based wash. That is, the amount of organisms in the “after” sample was clearly less than the amount of organisms in the “before” sample.

When engaging in the daily activities of life, we encounter “unexpected results” from time to time. The same is true in the lab. The same is true in these hand hygiene results. In some cases, there was no apparent improvement in the “before” and “after” samples. On a couple of plates, there were large colony spreads making interpretation impossible.  These unexpected results could be due to contaminated media surface, contaminants from the air or breath falling onto the medium, improper sampling, or improper disinfection. In all of these unexpected results, there is no cause for alarm.

We find in the laboratory that sometimes unexpected results happen and we cannot explain why. Most often, we will repeat the experiment and the unexpected will resolve. Sometimes, though, it is out of the unexpected that scientific discovery occurs!

Data Table for Hand Hygiene Culture Results:

  Pre-Wash Post-Wash
#1
++++
>1 colony
#2 +++ -
#3 +++ -
#4 ++ 1 colony
#5 ++++ >1 colony
#6 +++ -
#7 +++ -
#8 +++ -
#9 +++ -
#10 +++ 1 colony
#11 ++++ -
#12 ++++ 1 colony
#13 ++++ >1 colony
#14 ++++ >1 colony
#15 ++++ -
#16 ++++ -
#17 ++ -
#18 ++++ >1 colony
#19 ++++ -
#20 ++++ -
#21 Spread Spread
#22 ++++ -
#23 + -
#24 +++ 1 colony
#25 + -
#26 ++++ ++++
#38 ++ -
#39 +++ -
#40 ++++ ++++
#41 ++++ -
#42 +++ -
#43 ++++ ++++
#44 ++++ ++++
#45 ++ -
#46 ++++ -
#47 ++++ >1 colony
#48 ++++ -
#49 Spread Spread
#50 ++++ 1 colony

Pictures of Hand Hygiene Plates:
The pictures are arranged in numerical order in groups of threes.

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