Germ Science: Why Handwashing Matters

What You Need:

• Two or more slices of wheat or dark bread. (White bread takes longer to grow mold because it has so many preservatives in it, unless, of course, it’s homemade!)
• Zippered sandwich bag for each slice of bread
• Tongs
• Permanent marker
• Plant mister

What You Do:

1. Set it up. This works best if you and your child set up the experiment after a trip to the playground (or other similarly dirt-laden fun) and before he or she washes hands.
2. Ask your child to “wipe” off his or her hands to get rid of visible dirt. (Most children believe this is clean enough!)
3. Help your child use the permanent marker to label two sandwich bags: “Touched” and “Not Touched.”
4. Let your child use the tongs to remove a slice of bread from the wrapped loaf and place in the sandwich bag marked “Not touched.”
5. Let your child take another slice of bread and rub his or her hands thoroughly on both sides of the bread. He or she should put this slice into the bag labeled  “Touched.” Before zipping the bag, allow your child to give one to two gentle mists of water into each bag. Zip the bags and tape or place on a shelf, in a closet, or inside a cupboard. Check the bags every few days. Which one grows the most mold first?

What's Going On? Mold will grow on both slices, but much sooner and more abundantly on the “Touched” slice. Help your child understand that the germs that he or she did not see on the “wiped-off” hands became food for the mold. We certainly wouldn’t want to eat those germs, would we? Best to wash them off before we handle food! Teach your child to sing following song while scrubbing hands at the sink. It will keep them scrubbing long enough to get the germs off!

The Handwashing Song (To the Tune of Frere Jacques)

Over, under

Over, under

Scrub between

Scrub between

Rinse the tops and bottoms

Rinse the tops and bottoms

Hands are clean!

Hands are clean!