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Microbes—They’re Everywhere!Microorganisms and Handwashing

Background School is in session and there is excitement in the air—or are those germs?! Classrooms everywhere are full of children and therefore the numerous microorganisms that all people carry. Highlighting the microscopic world of germs and teaching good hygiene practices will help keep students healthy all year long. Microorganisms are ubiquitous—that means they are everywhere—and are often invisible to the naked eye. While microorganisms may live everywhere, most are harmless. It’s the few malicious, pathogenic, and contagious microbes generally called germs, that require intervention to avoid illness. Despite the fact that you can’t see them, there is actually a wide variety of shapes, sizes, and types of microorganisms at work in the world. Most can be classified as bacteria, viruses, protozoa, or fungi, and inside of each of these categories are species that can be helpful, harmful, or neutral to humans. All people are hosts to microorganisms. It is important to remember that our bodies are colonized with germs, which is called our “microbiome.” In fact, in a healthy adult, microbial cells are estimated to outnumber human cells ten to one (source: NIH Common Fund). Scientists have been working on a project called “The Human Microbiome Project” which has created a “map” of this biome by studying and recording the microbes in healthy people. Humans aren’t the only ones with bacteria either. In fact, cows must rely on the bacteria in their stomachs to digest their food—they can’t do it alone! When people get together, the microorganisms that live on them may spread. We don’t even have to touch each other to trade germs, it can be as simple as using the door knob or picking up a piece of paper that someone sneezed near. People can also pick up germs from other places like food and soil. In most cases, people won’t even notice that there are new germs on their hands or even in their mouths. But sometimes, there are “bad guys” that can make us sick. The goal of handwashing and other forms of good hygiene practices, like cleaning and disinfecting shared desk surfaces, carefully handling food, and covering your mouth when you sneeze, is to prevent the bad germs from getting into our system and making us sick.

Activity Procedures Activity 1: Handy Health Tips1. Talk with the students about where microorganisms can be found. Remind

them that microbes can be helpful, harmful, or harmless and share some of the situations listed in the “Are you Petri-fied of Germs?” article (attached).

2. Use this activity to show students the importance of washing hands with soap and warm water: a. Apply cooking spray or vegetable oil to each student’s fingers. b. Sprinkle cinnamon on the palms, backs, and in-between each student’s hands. The cinnamon represents germs that get on our hands. c. Try to get rid of the cinnamon using only cold water. d. Try to get rid of the cinnamon using soap and cold water.

PurposeThis lesson plan will help students understand the role that microorganisms play in the world and will highlight several methods of controlling microorganisms.

Time: Two 30-minute activities and one 45-minute activity, plus observation time

Grade Level: Elementary

Materials

Activity 1 � Cooking spray or vegetable oil � Cinnamon � Soap � Paper towels � Warm faucet water � Cold faucet water

Activity 2 � “A Germ of Truth” activity sheet

Activity 3 � Four potatoes—washed, peeled, sliced into 1/4” rounds, and microwaved for 1-2 minutes

� Plastic resealable sandwich bags (two per group)

� Permanent markers � Soap and water � Hand sanitizer

Supplement this lesson plan by reading Germ Stories, an illustrated book of poems by Arthur Kornberg

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e. Try to get rid of the cinnamon using soap and warm water. The cinnamon “germs” will rinse right off the student’s hands and into the sink. f. Ask the students why the cinnamon stayed on their hands until they used soap and warm water. How is this similar to washing germs off of our hands? Is it important to use soap and warm water for hand washing?

Activity 2: A Germ of Truth1. Have students pair up and give each pair a copy of the “A Germ of Truth”

activity sheet. (You may also choose to project this handout or have students use the online version.)

2. Inform students that the handout contains excerpts and graphics from different types of literature. Ask students to identify each item as “fiction” or “nonfiction” on the activity sheet.

3. Have students use the excerpts to create a one-page fact sheet on germs. If you wish, they can supplement their fact sheet with other research materials.

4. Have a discussion about different writing styles and then pose the question: can we still learn facts from fiction? How do you know when a fictitious story is using facts?

Activity 3: Cultivating an Understanding of MicrobesLike all living organisms, microbes need food sources to survive. Some microorganisms even like the same foods humans do! With this experiment, you will be able to “cultivate” colonies of microbes that students can observe while also highlighting the importance of good hygiene practices.

1. Prepare the potatoes before beginning this activity. Peel them deeply, then cut them into round, 1/4” slices. Microwave the slices for 1-2 minutes, until just soft. Note: Because potatoes are grown in soil, this experiment will not be sterile. You may want to introduce students to the concepts of safe food handling practices that farmers and grocery stores observe, pointing out that, while the foods are kept safe, there is no way to make them sterile (for more information, order “The Safe Food Journey” poster, free to Utah teachers through the Utah Agriculture in the Classroom website). By cooking the potato and limiting the amount of contaminants that touch the potato before the experiment starts, you will see greater differences later on.

2. Have students pair up and give each group two resealable plastic bags. Students should label the bags A and B. Make sure that everyone knows that bag A will be for the hand wash test and bag B will be for the hand sanitizer test. You may want to record this information on the board to help students avoid confusion. Students may decide between themselves who will perform test A and who will perform test B.

3. Have all test A students take turns thoroughly washing their hands, then as they return to their desks have them take a potato slice. Without touching anything else, students should rub the potato between their hands and then place it into bag A, sealing the bag closed.

4. Next, test B students should apply the hand sanitizer. They will also take a potato slice, rub it all over their hands, and seal it into bag B.

5. Microorganisms will grow best if the potato slice is very moist. If the potato slices in the baggies seem dry, you may have students add a little moisture using either an eye dropper or a spray bottle.

Vocabularybacteria: any species in a large group of single-celled microorganisms that lack organelles and organized nuclei; some species can cause disease

virus: a small infectious agent that can replicate only inside the living cells of an organism

mold: a term used to describe the visible growth of many different types of microorganisms, but usually indicates the presence of fungi

spore: a microscopic, one-cell unit that is produced by a fungus (or some forms of bacteria and algae) that can grow into a new organism when the conditions are right

fungus: any species in a large group of spore-producing organisms that may be one- or multi-celled and feed on organic matter; examples include yeast, molds, and mushrooms

medium: any substance that is used to grow microorganisms

microorganism: any organism of microscopic size

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6. Once students have completed the experiment procedures, have them answer the following questions in a science journal:

• What is this experiment designed to test?

• What do you predict will happen in each of the bags?

• What are the variables in this experiment? What could be changed to influence the outcome?

7. Collect the baggies and place them in an out-of-the-way spot (dark, warm conditions will yield the quickest results) for one or two days. Microorganisms will soon be apparent. Note: right after potatoes are peeled and cut, they may discolor and turn brownish. This is normal, but be sure to tell students that this is not due to microorganisms (it is a process of oxidation) and to watch for other signs of microbes that will appear over the course of a few days.

8. When the microorganisms begin to appear, return the samples to each group and have them record their observations, but give them the following warning: DO NOT OPEN THE BAGS. The bags are contaminated with microorganisms that could make people sick, and will stink up the classroom at the very least. Students should only observe the samples through the plastic. Have each student add to their science journal by sketching and describing their observations. Be sure that any students that handle the bags wash their hands afterward.

9. Collect the samples and wait one or two more days, then repeat step 8. Results will typically show that hand washing is the most effective at reducing microbial growth; however, it is important to note that, since microorganisms are everywhere, contamination can cause samples to spoil even when you are trying to maintain high standards of cleanliness. Having results that vary from what is expected does not equal failure; it is just a reminder that microorganisms are a daily part of life and that the best thing students can do to avoid getting sick is to wash their hands before they touch anything that goes into their mouths and before preparing food.

10. At the end of the experiment, have students consider the following questions.

• Which potato slice appeared to have the most microbial growth when you examined them the first time? What about the second time?

• Can you see differences between the types of microorganisms that are growing on the potatoes?

• What did this test teach you about microorganisms? (They are everywhere, but you don’t have to be afraid if you take simple precautions.)

• What can we learn about preventing the spread of microorganisms? (Hand washing is the most effective method.)

• What are some places that microorganisms live?

• Since farmers harvest their potatoes in the fall and store them for use during the rest of the year, what can be done to keep them from spoiling?

Potato slices with microbial growth after one week.

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Additional ActivitiesBecause cooked potatoes are an excellent food source for microorganisms, they can be used as the basis for many more microbial experiments:

• Where do microorganisms grow? Try rubbing the slices on light switches, tissue boxes, the floor, etc. and comparing them with the results from the experiment in Activity 3 of this lesson plan.

• What keeps microorganisms from growing? Treat slices with vinegar, salt water, sugar water, and rubbing alcohol to explore what types of preservatives can keep microorganisms from growing.

• What do microorganisms like? Try subjecting the potato slices to different conditions: sunlight, artificial light, and dark; hot and cold; moist and dry. See what makes microorganisms grow fastest and slowest.

Protect! Don’t Infect: Germ Wars (Video)Looking for more motivation to get kids washing their hands? Watch this fun, award winning video about how germs are spread from person to person... from the germ’s point of view! This light, understandable seven-minute video can be found on YouTube at http://www.youtube.com/watch?v=jDwrTJ9qqPM.

Are you “petri-fied” of germs? When is it okay to be afraid?The world is a petri dish, but microorganisms are a normal part of life. Germaphobia (scientifically called mysophobia) is an irrational fear of microorganisms and germs. But there is no need to fear! Simply understanding the diverse world of microbes—the good guys and the bad guys—can help children understand when risks are more or less serious. Here are some common concerns about germs.

Concern: If you can’t see germs, how can you avoid them? Response: Often times, you can’t. But don’t let this get to you—your immune system is designed to keep you healthy and to help you get better when you do get sick. It is impossible to avoid all microorganisms, but you can be careful around certain “hot spots” of germ activity. These include places that many people touch—like doorknobs and pencil sharpeners—and places that get high concentrations of germs—like water bottle tips, tubes of lip balm, and tissue boxes.

Concern: Someone threw up on the playground. What should I do? Response: There are lots of reasons that kids throw up, but regardless of the reason, all bodily fluid contain massive amounts of germs and microbes, so it is best to leave cleanup to a professional. Tell a teacher right away. The teacher will get a custodian who will use a special “body fluids cleanup” kit.

Concern: I ate a snack without washing my hands. Am I going to get sick? Response: Maybe. You just ate lots of microorganisms, so it depends on what kind they were. Many germs are destroyed by saliva and stomach acid, but sometimes the bad ones still make it through. Don’t be terrified—if you do get sick it will usually only be a few days of feeling icky—but you should definitely remember to wash up next time!

Concern: I like to push the cart at the grocery store, but I have heard there are germs on the handle. Response: Many grocery stores offer disinfecting wipes near the front door to clean carts. Offer to wipe the cart down and then promise to wash your hands before you eat... and then maybe your mom will change her mind.

Concern: I love yogurt, but the container says there are “live cultures” in it. What does that mean? Response: Remember that not all bacteria are bad. Some don’t do anything to humans, and some are actually good for us! The bacteria that grow in yogurt, called lactic acid bacteria, are an example of good bacteria. They turn liquid milk into creamy textured yogurt, which preserves the milk for a longer period of time and also turns the lactose (a protein in milk to which some people are allergic) into lactic acid, which is easier to digest and gives yogurt that delicious tart flavor.

A Germ of TruthEach of the following excerpts and images tells a story about germs. Can you tell fact from fiction? Hint: Sometimes fiction can contain facts, but informational texts never use fiction.

Excerpt from “Staphylococcous Aureus - Food Poisoning” From Germ Stories, a collection of poems by Arthur Kornberg

Staph aureus is on your hands and in your hair. It’s in your nose—it’s everywhere!

If you prick your skin, it enters and thrives: Millions of germs, very much alive.

From a baker’s hand on a rare occasion Some Staph broke out for a new invasion,

This time into a warm custard pie Baked that day. Oh, dear. Oh, my!

In the pie, germs grew and frolicked And spewed out poisons that can cause colic.

Under a very high magnification of 20,000x, this scanning electron micrograph (SEM) shows a strain of Staphylococcus aureus bacteria.

Picture and information provided by Centers for Disease Control and Prevention’s Public Health Image Library.

Red Bread

Excerpted from Food Intruders, by Karen M. Leet

Possibly the weirdest bread spoiler is not a fungus but a bacterium that’s only one one-thousandth of a millimeter long. It causes wet red spots on bread and has the disgusting name of bleeding bread.

Health experts say not to eat moldy food—or “bleeding” food either. Molds can cause breathing and allergy problems. Some molds make a poison called mycotoxin, which can make people very sick. If you find moldy or rotting food, throw it away and clean up the area where you found it. You don’t want any of those microbes spreading around.

Excerpt from “Surprisingly Hardy Flu Germs”

By Stephen Ornes, Published December 14, 2011 in Science News for Kids (full version is available online)

For a human, an infection often means getting sick. But for a virus, an infection means survival.

Viruses are tiny, disease-causing germs that can reproduce only inside organisms they’ve invaded. If these microbes end up outside the body, expelled through the nose by a sneeze or wiped on a sleeve, it’s hard for them to survive. When they’re unable to infect anything, viruses dry up and eventually die.

But that might be a long time, according to a team of scientists in France that recently put nasty viruses to the test. The team found that under the right conditions, a virus outside a host might survive and be able to cause infections for more than six months.

The scientists tested samples of the virus that causes H1N1 flu, better known as swine flu. The scientists found that the viruses sputtered out a day after being immersed in hot temperatures and surrounded by salty water. But at cooler temperatures and in less salty water, H1N1 retained its ability to cause infections for months.