Preschoolers understand the importance of hand washing when their hands are covered with something they can see like dirt or food, but preschoolers often have a hard time understanding why they need to wash their hands to get rid of germs that they can’t see. This simple preschool science lesson can help preschoolers understand why washing their hands can keep them healthy even when they can’t see the germs by transforming germs into something visible and teaching preschoolers how they spread.

What You Need

Chalk, colored sugar, or flour
A heavy rolling pin or a can
A cookie sheet
A black t-shirt

What To Do

Ask preschoolers if they know what germs are. Tell them that germs and viruses are too small to see but they can make us sick. Explain that germs can spread when we touch something that has germs on it and then touch our eyes, nose, or mouth.

Have preschoolers put the chalk on a cookie sheet and use a heavy rolling pin or a can to crush it into a powder. If using sugar, mix it with a small amount of food coloring or natural food dye such as spinach juice or beet juice.

Spread the crushed chalk or other material on the cookie sheet and have preschoolers coat their hands with the powder. This activity is most effective when done while wearing a black shirt so preschoolers can see the spread of germs. Have preschoolers walk around the house and shake hands or touch each other’s clothing and watch what happens to the “germs” that are on their hands.

Ask preschoolers why it is important that they wash their hands. Have preschoolers wash their hands with soap and water and watch the germs wash away. This lesson can be an important reminder to preschoolers to wash their hands. If preschoolers complain about having to wash their hands, simply remind them of this germ activity and ask them if they want to share their germs with their friends or wash their hands so they can stay healthy.