When this article appeared during the COVID-19 pandemic, handwashing was a prominent public-health message. While some of us were already good handwashers, and some have become good handwashers as times have changed, others still just aren’t getting it!
If you were in any doubt about just how important handwashing is just have a look at this experiment that was carried out by a teacher in Idaho. Please note that while this experiment was carried out before the COVID-19 pandemic, it just goes to show you that we should have always been using good hand cleaning techniques and practices. The 2020 feature reported more than 70,000 Facebook shares at that time; that number describes its circulation, not the strength of its evidence.
Before the 2020 feature was published, Jaralee Metcalf, a behavioural specialist from Idaho Falls Elementary School, decided she was fed-up with always being sick. Although around small children the spread of bacteria is inevitable, she nevertheless wanted to show her class why cleaning their hands matters.
To carry out the experiment, the class compared five conditions involving slices of white bread. The account describes sealing the bread in plastic bags and observing it for a month, with the bags reportedly stored under the same conditions. The cases included a device surface, an untouched control and three hand-cleaning conditions.
The slices of bread went as follows:
1. Was rubbed on all the Chromebooks in the class
2. Wasn’t touched – this was the ‘control piece’
3. Was touched by the class using unwashed hands
4. Was touched by the class using hands cleaned with soap & water
5. Was touched by the class using hands cleaned with hand sanitiser
The reported differences after one month were visually striking.
According to the classroom account, the slice rubbed on the Chromebooks showed the most visible growth after a month. The slice touched with unwashed hands also showed extensive growth. Some growth appeared on the slice handled after using hand sanitiser, with less reported than on the unwashed-hand and Chromebook slices. These are observations of appearance: the photographs do not identify bacteria, count disease-causing organisms or measure how well a product prevents infection.
The account reported very little visible growth on the bread touched by hands cleaned with soap and water and described it as looking similar to the untouched control. That visual similarity does not establish that either slice was sterile.
If you share the classroom story with friends or family, include both the handwashing guidance and the limits of this demonstration. The photographs can start a useful conversation without being presented as proof that hand sanitiser fails or that visible growth measures every infection risk.
What the bread photographs can and cannot show
The restored classroom account preserves the five comparisons and the teacher’s images. The distinction between an observation and a controlled test is essential to reading them accurately.
Observation is different from proof
A slice that looks different gives students something to investigate. It does not, by itself, identify the organisms present, measure how many disease-causing germs were on someone’s hands, or show whether a virus was transmitted. A bread photograph is not a diagnostic test.
Likewise, comparing a few slices cannot establish that hand sanitizer never works. Handling, storage and differences between slices can affect the result. To compare cleaning methods reliably, an investigation would need repeated trials and a way to measure the outcome consistently.
What to do at the sink
The CDC’s everyday handwashing guidance is straightforward: wet your hands with clean running water, apply soap and lather all over, including between fingers and under nails. Scrub for at least 20 seconds, rinse and dry with a clean towel or an air dryer.
Wash before eating or preparing food, after using the toilet, and after blowing your nose, coughing or sneezing. When soap and water are unavailable, the CDC recommends a hand sanitizer containing at least 60% alcohol.
A better classroom question
Ask students to make two lists: “What we observed” and “What we would need to test.” That small change keeps the curiosity while avoiding an exaggerated conclusion. A good science lesson can teach both a useful daily habit and the patience to ask what the evidence really supports.
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