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The Bread and Germ Experiment


I came across the Bread and Germ Experiment a couple of years ago when I was searching for healthy living topics that were not related to fitness. Popularized on a few news articles and blogs, it is where you have 4 slices of bread, each exposed to a different amount of germs before being placed in a sealed Ziploc bag. 


1. Control Bread (no contact, from store to sealed bag)

2. Soap Washed (hands were washed with soap and water for 20 seconds)

3. Water Washed (hands washed with water only for 10 seconds)

4. Unwashed (hands were not washed all morning before touching bread)


With the COVID-19 pandemic, I saw an opportunity to make this a meaningful experiment with real-world links, and a bonus of seeing bread look increasingly fascinating and disgusting over time. While I originally planned for this to be explored on our return to in-person school, I adjusted it for an online school setting. Here is how I went about doing it with my Grade 3 and 4 classes and the results you can expect:


Tuning In


In lesson one, I introduced my classes to the experiment with a brief description and picture of the 4 pieces of bread in their sealed, labeled bags. The two questions I asked them to answer were:


  1. What do you think will happen to the different slices of bread?

  2. What do you know about germs?


These responses shaped how much scaffolding would be needed and how in detail I could look to go with connecting this to COVID-19 next week.

Week 1 Bread.jpg

Finding Out


In week 2 we looked at the changes in the bread. As processed bread does take a long time to start molding, the only change was faint green spots forming on the unwashed Hands bread. 

  1. Do you think the other pieces of bread will also change?


Students also watched a BrainPOP video on COVID-19. This kid-friendly video clearly explained what COVID-19 was, and the precautions that should be taken. Accompanying this video I asked:


  1. What similarities are there between preventing common germs and preventing COVID-19?

  2. Where can you go to find more information on COVID-19 and germs?


Students were well informed after the BrainPOP video to answer these questions with many responding that you should wash hands with soap for both and avoid touching others. (like the control bread). 

Week 2 Bread.jpg

Going Further


Week 3 finally saw the changes I was waiting for! As predicted, the unwashed hand's slice of bread molded at a much faster and larger rate, with the water washed hands following it at a slower rate of change. The soap washed hands bread saw a couple of green spots occur as well. 


I asked students one question, before assigning their main task for the week. This was:


  1. After seeing how the germs have appeared on the different pieces of bread, what will you make sure to do daily?


The main task was for them to create a poster (offline) of the importance of washing hands. They were asked to include drawings, two or more facts about germs, and how to properly wash your hands. Any bonus information was encouraged!

Week 3 Bread.jpg

Making Conclusions


To wrap up this experiment I shared one last picture of the bread slices clearly demonstrating the differences between each piece. I wanted to draw their focus to the minor mold on the Soap Washed hands piece of bread, before having them reflect on the entire inquiry.


  1. Does the mold on the Soap washed hands slice of bread mean that hand washing doesn’t work?

  2. Was your prediction at the beginning of the experiment correct? Why or why not?

  3. What can you do with this information from the experiment?

Week 4 Bread.jpg

Teacher Reflection


This was a lot of fun to do online and was a nice change from the online learning fitness unit students were working through as well. However, I originally planned for this to be an experiment done at school. This would have allowed for a greater link to physical health and would have included more germ themed games! Instead of being a weekly conversation, I would have spent 5-15 minutes on the experiment each class over the month (8, hour long classes)


Here is my original plan:

The Bread and Germ Lessons.png

Have you done this experiment in your classes? Anything you would change? Let me know any questions, concerns or feedback on twitter @tannernickel.

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