6 - 8
Two class sessions, plus 10-minute daily observations for one week
In this lesson students will learn about foodborne illness, its prevention, and the people and organizations that are involved in food safety. Students will conduct an experiment to learn how hand-washing affects the presence of bacteria on their hands.
For the teacher:
- Perils at the Picnic
- Food Safety Sleuths PowerPoint
For each group:
- Four sterile nutrient agar plates
- Clear tape
- Resealable plastic bag
- Permanent marker
- Heat lamp or incubator (optional)
- Soap, water, and paper towels
- Hand sanitizer
- Presentation rubric
For each student:
- Hands On! lab worksheet
- Perils at the Picnic handout
- Food Safety Sleuths handout
Essential Files (maps, charts, pictures, or documents)
Food Safety Sleuths PowerPoint
Perils at the Picnic
Hands On! lab worksheet
Food Safety Sleuths handout
virus: extremely small organism that causes disease and can spread from one person or animal to another
pathogen: something that causes disease or illness.
parasite: an animal or plant that lives in or on another animal or plant in order to get food and protection.
microorganism: any organism, such as a bacterium, protozoan, or virus, of microscopic size.
innoculate: to introduce a microorganism into a suitable growing medium.
foodborne illness: any illness resulting from the consumption of food contaminated with viruses, parasites, or pathogenic bacteria.
food safety: the handling, preparation, and storage of food through scientifically tested methods that prevent foodborne illness.
contaminate: to make something dirty or impure by accidentally or purposely adding something harmful.
bacterial colony: a visible cluster of thousands of cells that grew from the original bacterial cell. One single bacterium is invisible to the naked eye, but a colony of many bacteria is visible without using a microscope.
agar plate: a Petri dish containing a gel with nutrients for growing bacterial cultures or small plants.
Background - Agricultural Connections
This lesson is one out of four lessons designed for grades six through eight which promote the development of STEM abilities and critical thinking skills, while fostering an appreciation for the people involved in food production. The new curriculum includes inquiry-based labs, real life challenges for students to investigate and opportunities to plan and construct products and shipping models. Other lessons in this series include:
- Mix It Up! Food Scientist
- Cruisin' for a Bruisin' Food Packaging Specialist
- Food on the Move Food: Transportation Specialist
- Food Safety Sleuths- Food Safety Specialist
A foodborne illness is when a person becomes sick after consuming food that is contaminated with:
- microorganisms such as bacteria, viruses, and parasites
- chemicals such as household cleaners
- physical objects such as glass or metal
Symptoms of foodborne illness include upset stomach, nausea, vomiting, stomach cramps, fever, and diarrhea. Microorganisms play a role in the majority of foodborne illnesses. Most microorganisms are harmless, yet some can make us sick. The microorganisms that cause illness are called pathogens.
- Viruses are the smallest forms of life on Earth, yet cannot reproduce outside of a living host cell. Viruses are responsible for illnesses like colds and flu. Hepatitis A and norovirus are examples of viruses that cause foodborne illnesses.
- Parasites are tiny organisms that require a host to live. Examples are amoebas that may be found in unclean drinking water, Anisakis roundworm that can be found in fish, and Trichinella spiralis that may be found in pork.
- Fungus including yeasts and molds are often used in making foods such as bread and cheese, but can also spoil food and make people sick.
Bacteria are single-celled organisms. While most are harmless, some are pathogenic. These pathogenic bacteria are often responsible for most cases of foodborne illness. Using nutrients found in food, bacteria can quickly multiply under the right temperature conditions. As bacteria multiply, they excrete toxic waste products that can make people sick after consuming contaminated food. If conditions are favorable, bacteria numbers can double every ten to thirty minutes. Proper food handling, storage, and preparation can prevent most foodborne illnesses caused by the pathogens described above. There are many careers dedicated to keeping our food safe. These careers involve the latest in science and technology to find new methods of providing people with a healthy food supply. The U.S. Department of Food and Agriculture (USDA) regulates meat, poultry, and eggs, and the U.S. Food and Drug Administration regulates the rest of the food produced in or imported into the country. Local health inspectors regulate restaurants, supermarkets, and other food service businesses and organizations in our communities.
In general, a food safety specialist’s job is to make sure that our food is wholesome and safe by applying their knowledge of food science, bacteriology, microbiology, food laws, regulations, and hazard analysis. Food safety specialists work in hotels, government agencies, restaurants, factories, and more. There are a wide range of employment opportunities and careers linked to food safety. Visit the USDA Food Safety and Inspection Services website www.fsis.usda.gov and select Careers then Opportunities and Types of Jobs to read descriptions of duties and qualifications.
Everyone can play a role in preventing foodborne illness. Food safety specialists recommend following four simple steps before handling or eating food: clean, separate, cook, and chill.
- Wash hands with soap and water for 20 seconds or for the length of time it takes you to sing the happy birthday song twice.
- Wash utensils, cookware, and surfaces with soap and water.
- Rinse fruits and vegetables with water. (Do not wash meat or eggs.)
- Cover your mouth and nose with your elbow when coughing or sneezing. Wash your hands after blowing your nose.
- Use separate cutting boards and plates for raw produce, meat, poultry, seafood, and eggs.
- Bacteria that cause food poisoning multiply quickest between 40 degrees Fahrenheit and 140 degrees Fahrenheit—this temperature range is known as the Danger Zone. Cooked food is safe after it has been heated to at least 140˚F. Use a food thermometer to check the temperature of cooked food. Microwave foods to 165˚F.
- Refrigerate perishable foods within two hours to slow the growth of illness-causing bacteria. Refrigerators should be kept between 40˚F and 32˚F, and your freezer should be 0˚F or colder.
- Don’t thaw or marinate foods on your kitchen counter or table. Instead, thaw food in the refrigerator or microwave and marinate in the refrigerator.
Interest Approach – Engagement
- Show your students the Recipe for Disaster video clips located on the foodsafety.gov website. Each video illustrates a food safety mistake that could be made in the kitchen while preparing food. Lead a discussion with your students about each mistake Maria makes.
- Inform your students they will:
- learn how to prevent foodborne illness through safe food handling and preparation;
- learn how environmental factors influence bacterial growth;
- design an experiment to test a hypothesis; and
- identify different types of bacterial pathogens that can lead to foodborne illnesses.
- Ask students what comes to mind when they hear the words food safety, and jot some of their ideas on the board. Discuss an example of safe food handling practices at a picnic. To provide students with background information on the topic of food safety, read Perfect Food Safe Picnics! and compare the information found in the article with students’ initial ideas about food safety.
- Tell students that you will read a scenario to them about a group of friends who go on a picnic. Instruct students to pay close attention to food safety issues as you read the story aloud.
- After reading Perils at the Picnic to the class, ask students what they noticed about food safety at the picnic. Ask students if they would have done anything differently and why.
- Organize students into groups of 3-4 and pass out Perils at the Picnic along with the accompanying Cracking the Case questions. Have each group brainstorm answers to the Cracking the Case (page 2) questions. Review answers as a class.
- Show students the Food Safety Sleuths PowerPoint presentation. Students should use the Food Safety Sleuths handout to take notes.
- At the end of the presentation, have students break into groups to come up with a catchy rhyme or song to remember the four steps for food safety. Clean, Separate, Cook, and Chill.
- Explain to students that they will be conducting an experiment to learn how hand-washing affects the presence of bacteria on their hands. Organize students into groups of 3-4 and instruct them to brainstorm methods they could use for testing the effects of hand washing on the presence of bacteria. Groups should write down their ideas about experiment set-up and should share them in a class discussion.
- After the class discussion on experimental design, distribute the Hands On! lab to each student and go over the directions as a class. Explain that this is one example of how a hand-washing experiment could be carried out and discuss its similarities to ideas that groups had while brainstorming experiment set-ups.
- Demonstrate the proper sterile technique for inoculating the nutrient agar plates.
- Instruct students to design a slide show, video, poster, or brochure describing food handling and preparation techniques. Students should use data from their own experiments as well as facts from research. Review the presentation rubric with the students.
Concept Elaboration and Evaluation
After conducting these activities, review and summarize the following key concepts:
- Foodborne illness is any illness resulting from the consumption of contaminated food.
- Food contamination can take place as a result of poor storage of food, improper cooking, or cross contamination while preparing food.
- Hand washing is an important step to protect yourself and others from foodborne illness.
- Food Safety Specialists help increase and improve the safety of our food supply.
- Allow students to alter the Hands On! lab experiment by culturing swabs from raw and cooked chicken or beef.
- Use Glo GermTM lessons and products to teach proper handwashing techniques.
- Use visuals to show images of proper food safety procedures.
- Demonstrate lab procedures and show examples of completed lesson tasks.
- Use a word wall to chart different types food storage, handling, and preparation techniques.
- Do a computer search at www.AskKaren.gov and select the En Espanol option.
We welcome your feedback! Please take a minute to tell us how to make this lesson better or to give us a few gold stars!
- View the Recipe for Disaster video clips located on the foodsafety.gov website.
- Suggest a focus group study on food safety for pets.
- Invite a guest speaker from a local supermarket, restaurant, or food distribution businesses to make a presentation to the students about their food safety programs and career opportunities in their fields.
- Have students research modern food preservation techniques such as canning, freezing, dehydrating, and pasteurization and compare and contrast them to historic techniques.
- Research historical food contamination tragedies.
- Watch food safety videos from the USDA. From the YouTube home page, type in "cook it safe."
Suggested Companion Resources
The 12 Most Unwanted Bacteria (Activity)
Imported Food Safety (Activity)
Glo Germ Set (Activity)
Food Safety from Farm to Fork: Playing it Safe (Activity)
Food Safety from Farm to Fork: Operation Kitchen Impossible (Activity)
Food Safety from Farm to Fork: Mighty Microbes (Activity)
Food Safety from Farm to Fork: How Fast Will They Grow? (Activity)
Career Trek Game (Kit)
Virtual Labs: Understanding Water Activity (Multimedia)
How Safe is Your Salad? (Multimedia)
You're Hired! (Multimedia)
Virtual Food Safety Labs (Multimedia)
Food Safety Music (Multimedia)
Gourmet Lab: The Scientific Principles Behind Your Favorite Foods (Teacher Reference)
Feed, Nourish, Thrive (Careers Website) (Website)
Antimicrobial Wash for Fresh Produce (Website)
Fight Bac! Food Safety Education (Website)
This unit was funded by the United States Department of Agriculture’s National Institute of Food and Agriculture, Secondary Agriculture Education Challenge Grants Program.
Executive Director: Judy Culbertson
Illustrator: Toni Smith
Layout and Design: Nina Danner and Renee Thompson
Copy Editor: Leah Rosasco
Mandi Bottoms & Shaney Emerson
California Foundation for Agriculture in the Classroom