This fun, easy to put together experiment is designed to teach students ages 3 and up about washing hands, how germs spread and how they grow. It is also designed to teach older students about the scientific method and record keeping.
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- 5 pieces of plain white bread
- 5 sandwich-sized ziplock bags
- Some hand sanitizer (rubbing alcohol will do in a pinch)
- A bar of soap
- Household gloves
- The experiment record sheet (download at the bottom)
The purpose of this lesson is to show students that we can spread germs even if we can’t see them. For older students, the secondary purpose is to understand the scientific method.
Contamination, spread, hypothesis, scientific method
For this experiment, ask all members of your household to participate.
Spray all five slices of bread with water, don’t soak it but make sure the bread becomes moist. Be careful not to touch one piece of the bread (use gloves to hold it).
Pick up one slice of white bread with gloves or a paper towel and carefully place it, untouched by human hand, into one ziplock bag. Mark on post-it notes or a label – “untouched,” and fix the label to the bag. Seal the bag, leaving some air inside.
For the next four slices do the following:
First slice: everybody in the household rubs hands dirty hands over the bread. Mark this bag as “dirty hands”
Second slice: everyone in the household washes hands with soap and water. Everyone in the household rubs their hands over the bread. Mark this bag as “soap and water hands.”
Third slice: use hand sanitizer on everyone’s hands. Rub your hands over the bread and mark the bag as “Sanitized hands.”
Fourth slice: Find a very dirty object, toilet or a sink or a keyboard. Next, rub a piece of bread over this object. Mark this one as “Dirty Object”
Finally, seal all five bags and place them into a warm, sunny area (like a windowsill).
Over time, mold will begin to grow.
• Ask younger students to make verbal predictions as to the outcome of the experiment. Will the bread look the same? Will germs start to grow on it? Where will the germs come from?
• Ask the older students to create a hypothesis as to what will happen next. Ask them to begin to record the results of their experiment on the “Experiment Record” sheet for the next 31 days.
• Ask older students to research the scientific method and to write about how the scientific method works.
• Learn more about this experiment here.
For more on the scientific method see these resources:
- BrainPop on Scientific Method (if you are affected by school closures, you can get a free membership, just send them a request)
- Sprouts on Scientific Method
- Scientific Method Book (free with kindle unlimited)
- Khan Academy on the scientific method
- Live Science on the scientific method
- Scientific Method educational poster
- Life on Us a Microscopic Safari (free with amazon prime)