Hand Washing Experiment for Kids

Hand Washing Experiment for Kids - Day 10 - by Little Spoons and Spice

When it comes to washing hands, teaching kids the why, is just as important as the how.  If they understand the importance of why we wash, then they’re probably more likely to remember to do so every time…. and to wash thoroughly.

To help our kids understand, we did a little experiment to show what happens to food when handled with dirty hands.  We took three pieces of bread. “A” was the control (not touched); “B” was touched with dirty hands; and “C” was touched with washed hands.  The kids were surprised as they watched the mold grow.

To try this experiment at home, here’s what you’ll need:

3 slices of bread (3-day old homemade bread works best as it lacks some preservative)

3 zip-lock bags

Marker/pen to label bags

Water dropper


  1. Place one slice of bread in a zip-lock bag. Try to avoid touching it.  If possible, use a cleaned and sterile tongs.  This will be your CONTROL piece.
  2. Next, have the kids go around the house touching a few door knobs, light switches and pen/pencils. These are things they touch every day but wouldn’t normally think their hands are dirty after touching.
  3. With dirty (unwashed) hands, have them handle a new piece of bread. Have their little hands touch all over the piece of bread to ensure adequate germ transfer, then place it in a new zip-lock bag.   This will be your DIRTY HANDS piece.
  4. Next, have them wash their hands thoroughly. With clean hands have them handle a new piece of bread then place it in a new zip-lock bag.  This will be your CLEAN HANDS piece.
  5. Take a small liquid dropper and sprinkle 0.5mL of water onto each piece of bread. This adds moisture which helps mold grow.
  6. Seal each bag. It’s best to store in a dark area, away from direct sunlight.  Now wait.  Visible mold may take up to 7-10 days to grow.


Day 1

Hand Washing Experiment for Kids - Day 1 - by Little Spoons and Spice

Day 10

Hand Washing Experiment for Kids - Day 10 - by Little Spoons and Spice

Day 15

Hand Washing Experiment for Kids - Day 15 - by Little Spoons and Spice

As you can see, the longer you wait the more mold you will grow.  It’s pretty obvious that mold will grow on old bread when moisture is added; however, when handled with dirty hands, the mold growth is enhanced, more wide spread, and more dense on the slice of bread.  Even the clean hands had more growth than the Control. This could be that one of kids may not have washed their hands as thoroughly as they should have.

According to the CDC, the proper way to wash hands is to follow these steps:

  1. Wet your hands with clean, running water
  2. Apply soap and rub hands together to create a lather. Be sure to scrub between fingers, under nails and the back of your hands.
  3. Scrub for 20 seconds. Have your kids sing their ABC’s to know how long they should wash their hands.
  4. Rinse hands with clean, running water.
  5. Dry hands thoroughly with a clean towel.


Why wash your hands?

Washing hands is a crucial step to prevent the spread of infections and illnesses.  Specifically, it can prevent the spread of salmonella, E. Coli 0157, norovirus, adenovirus and hand-foot-mouth disease.

In the kitchen, hand washing is foundational for food safety.  Hand washing not only helps prevent the spread of illnesses, but also cross contamination.  If you’re cooking with raw ingredients like eggs, your child could get sick if their hands are not properly washed after exposure. And if they don’t wash their hands after they use the bathroom, they could spread other germs (viruses and bacteria).


This experiment can open up a great dialog with kids.  Here are some discussion ideas and questions:

How many days do you think it will take to grow mold?

What color do you think the mold will be?

When should you wash your hands? (hopefully they create a long list)

Which fun songs can we sing, other than the ABC’s, while washing our hands?

How many bubbles do you think you can make when lathering soap?



“CDC Features.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 11 Oct. 2018, www.cdc.gov/features/handwashing/index.html.

“Handwashing: Clean Hands Save Lives.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 17 Sept. 2018, www.cdc.gov/handwashing/why-handwashing.html.

Leave a Reply

Your email address will not be published. Fields marked as * are mandatory