Handwashing Experiment

Have you ever “washed” your hands by just rubbing them together under running water for a few seconds? Try this experiment to compare different hand-washing methods and see which is most effective at getting rid of germs! (Note: This experiment takes more than a week to complete.)

What You Need:

What You Do:

  1. Have your adult helper wash his or her hands, put the gloves on, and cut the potato into four equal pieces.
  2. With the gloves still on, have your helper put one potato slice in a bag. Seal the bag. Use the marker to write on a piece of masking tape and label the bag as “control.”
  3. Next, rub your bare, unwashed hands all over the second potato slice. Place the slice in a bag and label it “dirty hands.”
  4. Now rinse your hands by lightly rubbing them together under running water, but don’t use any soap. Dry your hands, and rub them all over the third potato slice then place it in another bag. Label this bag “water only.”
  5. Next, wash your hands thoroughly with soap and warm water for at least 20 seconds. Dry them on a clean towel (not the same one you used after only rinsing your hands) and rub your hands all over the last potato slice then seal it in another bag and label it “soap & water.”
  6. Place all four bags in a dark area at room temperature, like a closet or cupboard. Leave them there for a week. After the week has passed, pull the bags out and look at the potato slices (but do not open the bags). What do you see on the potatoes? Which one has the most growth on it? Which potato has the least? (Note: If there wasn’t much to see on your potatoes, put them back in the dark spot for a few more days and then check them again.)

When you are done looking at the potatoes, have an adult pour a small amount of bleach into each bag, seal the bags, and then throw them away. (This is to kill all of the germs on the potato slices so that they can’t continue to grow after you throw them away.)

What Happened?

Do you see black, green, or white fuzzy spots on your potato slices? These are germs, called mold or bacteria, growing on the slices. While individual germs are too tiny to see without a microscope, now there are so many germs clumped together that you can see them with your naked eyes! The potato piece that you rubbed on your unwashed hands probably has the most growth on it. The “control” potato slice probably has the least amount of bacteria growing on it, because it didn’t touch anything that had germs. That potato piece is important because it lets you see how many germs already existed on the potato. The other potato slices probably had just as many germs on them from the start, but once they touched other things, they picked up more germs and the germs began to grow more than the germs on the first potato. Compare the potato pieces that you touched after rinsing your hands just with water and after washing well with soap and water. Which one has more growth on it? Do you think that washing your hands well with soap and water is better at getting rid of germs than just rinsing or washing quickly?

Science Lessons

What Are Germs?
Germs are microscopic organisms (or living things) that can make you sick. Microscopic means they are so small that you can’t see them unless you use a high-powered microscope. There are different kinds of germs, but the most common are bacteria (say back-TEER-ee-ya) and viruses (say VY-ruhs-iz).
Bacteria are tiny living creatures made of only one cell. They live just about everywhere and get their food from the environment they live in. Here’s an example: bad bacteria in your mouth like to eat the sugar that sticks to your teeth and can cause bad breath and even gum disease. Brushing your teeth helps prevent them.
Viruses are a little different. They survive by living inside the cells of a living thing such as a person, plant, or animal, called a host. Viruses can live for a short time on surfaces, such as a doorknob or faucet. They can quickly spread through the body and make the “host” sick. The flu, cold sores, and chicken pox are all caused by viruses.

Helpful Germs & Antibiotics
While it is easy to think that all germs are bad, most germs do not harm you at all and some are even good for you! For example, your stomach contains good bacteria that help you digest your food and produce vitamins to keep you healthy. Some germs are actually grown to be used as medicine to fight other germs. Penicillin is a common medicine that comes from a type of mold and kills many harmful types of bacteria. This is known as an antibiotic.
Some foods and other things we have around our homes have special antiseptic or disinfectant properties, meaning they can help prevent germs from growing and spreading! Soaps and cleaners that are disinfectant are used for cleaning surfaces of nonliving things, like your floors or countertops, while antiseptics can be used to keep cuts and scrapes on your skin clean and prevent germs from growing in wounds.  Remember that antiseptics and disinfectants are not the same as antibiotics.

How to Prevent Spreading Germs

Being a good hand washer is the best way to protect yourself from getting sick as well as preventing spreading your germs to others! Make sure to scrub in between your fingers and underneath your nails. Can you think of some times when you should wash your hands? Here are a few:

  • Before you eat
  • After you use the bathroom
  • After coughing, sneezing, or blowing your nose
  • After playing outdoors
  • After touching animals

Another good way to fight bad germs is to take proper care of your body. Eat lots of healthy foods like fruits, vegetables, and whole grains. These foods provide essential vitamins and minerals to help strengthen your body’s immune system (internal defense system), giving you a better chance to fight off germs that could make you sick. Getting exercise and plenty of sleep also helps support your immune system.
Germs are easily transferred to surfaces such as toys, doorknobs, faucets, and counters from normal daily activities. Wiping things down can help stop germs from being spread to others, especially when you or someone else in your family is sick!

Science Words

Bacteria – small, single cell organisms that live almost everywhere. Some are harmful, but most are harmless and even helpful.

Viruses – small disease-causing agent that lives inside the cells of larger organisms, such as plants, animals, and humans.

Antibiotic -a medicine that attacks bad bacteria to prevent illnesses.

Natural Antiseptics and Disinfectants
Here is a list of fairly common items that are naturally antiseptic or disinfectant. You may even be able to find a few of them around your home!

  • Raw Honey (Try it: the next time you get a minor cut, scrape, or burn on your skin, try gently spreading a little raw honey over the area and then covering it with a bandage. Just make sure you use raw honey – grocery store honey has been heat processed, which can take away some of the healing benefits found in raw, unheated honey! )
  • Lemon Juice (Try it: while you wouldn’t want to put this on a cut since its high level of acidity would sting, you can use it to keep things clean and smelling fresh. Try using half of a lemon to scrub grime out of a pot when helping with the dinner dishes.)
  • Grapefruit Seed Extract, Lavender, Eucalyptus & Tea Tree Oil are ingredients that are commonly used in natural skincare or cleaning products. They can act as preservatives to help keep bacteria, mold, or mildew from growing. They can also be used to freshen or sanitize the air in air freshener.
  • Rosemary, Lavender, Eucalyptus, and Tea Tree Oil all have natural antiseptic properties and essential oils from these are commonly used in many natural cleaning and skin care products.
  • Rubbing Alcohol & Hydrogen Peroxide are commonly used as antiseptics on cuts and scrapes. They can also be used to sanitize hard surfaces, like counter tops.
  • White Vinegar

How to Clean Mold & Mildew
Vinegar & Hydrogen Peroxide
Try it: Do you have any pink or black spots in the corners of your bathtub or bathroom? Try spraying the area first with vinegar and then with hydrogen peroxide (don’t rinse the vinegar off in between!). This should kill mold and mildew! You can wipe or rinse the area clean after letting it sit for a few minutes.
Tea Tree Oil (also called Melaleuca Oil) – tea tree oil comes from the leaves of melaleuca trees, which grow in Australia. Try it: mix 1 teaspoon of tea tree oil with 1 cup of water in a small spray bottle. Spray on a mold or mildew spot in your bathtub or shower and don’t rinse it away. It should kill the mold or mildew (but the strong smell of tea tree might remain for a few days!).