Sometimes, a hands-on demonstration speaks louder than words—especially for teaching children.
This U.S. teacher, Jaralee Metcalf, created a simple yet powerful experiment to illustrate the critical role of proper handwashing in preventing bacterial growth. The results are striking and educational.
Its clarity and simplicity make it an ideal teaching tool, which is why we're sharing it here.
Watch this experiment demonstrating the importance of handwashing for children.
Jaralee Metcalf, a school teacher in the United States, conducted this experiment at the start of flu season to teach her students about bacteria.
She needed an accessible way to demonstrate how handwashing combats germs. Using slices of sandwich bread from the same loaf, she had students touch five pieces under different conditions:
- Hands washed with soap and warm water.
- Hands sanitized with alcohol-based gel.
- Unwashed hands.
- Rubbed on a dirty computer keyboard.
- Touched with gloves (control slice).
Each slice was sealed in a plastic bag, hung on the wall, and observed for one month to track bacterial growth.
The results are eye-opening. Explore further: The 10 Dirtiest Objects in Our Daily Lives.
After one month, this slice was completely overtaken by mold—the worst outcome. As Metcalf noted, it underscores the need to regularly disinfect keyboards. (This one was not cleaned beforehand.)
Pro tip: Learn the best way to clean and disinfect your keyboard effectively.
The control slice (touched with gloves, on the right) remained pristine, as expected.
The only other intact slice? The one touched by hands properly washed with soap and warm water. A clear lesson in effective hygiene.
Dramatic mold growth in just one month—no further explanation needed. This drove home the message for her students.
Explore: Revive stale bread with this simple trick.
Surprisingly, this slice also developed significant mold. Proof that alcohol gel does not fully replace washing with soap and water.
Metcalf shared her findings on Facebook, urging parents to use them as a teaching tool for proper handwashing.
The experiment has since gone viral, inspiring replications in schools worldwide.
The gel result was particularly revealing. How do you teach your children to wash their hands thoroughly and often?
