About the Activity
This fun and educational activity will show kids how the body’s immune system works and how it protects animals and humans against sickness. Plus, there’s candy involved, so it should be a hit.
This is the first in a four-part educational series about preventing and treating illness in animals. View all activities at 4-H Veterinary Science: Stopping Sickness.
Topic: Animal Science
Estimated Time: 60 minutes
Supported by the Agriculture and Food Research Initiative, Education and Workforce Development Program.
These simple materials will get you started.
- A pencil or pen
- Internet access to research the immune system
- A bag of M&Ms, jellybeans or other multi-colored candy
- A calculator
- The downloadable activity guide with information on immune systems
Follow these steps to complete the activity.
Before we start, think about this: Having a fever is not fun, but when you — or an animal — are sick, it’s a good sign. That’s because fevers “turn on” the immune system, helping the body fight infection. So you may feel sick when you have a fever, but that’s because your body is working hard to protect itself!
- To start, read through the downloadable activity guide, glossary, and information about the immune system. There’s some pretty amazing stuff in there.Did You Know? Lymphocytes are white blood cells that support your immune system by attacking pathogens (any microorganism that can cause sickness in your body). They are found in the bloodstream and lymph nodes. Erythrocytes are red blood cells that carry oxygen from the lungs to the body’s tissues.
- Now it’s time for M&Ms! Open your bag of candy and sort the pieces according to color. Put the color group with the most pieces at the top of your working area; put the group with the second-most pieces below this, and continue until the group with the fewest pieces is at the bottom.Note: A typical bag of M&Ms has six colors in it, so if you don’t have enough different colors to do all eight of the blood cell types, that’s fine, the basic idea is still the same.
- Count the total number of “cells” you have and record this number.
- Assign a blood cell type name from the list in the matching activity to each color of candy.
- Finish performing your Complete Blood Count by counting the number of each color candy, then calculating the percent of each type of “cell.” The total of all candy percentages should equal 100.Tip: To calculate a percentage, divide the number of a specific color candy by the total number of cells. Then multiply that by 100 to convert that decimal to a %. For example, if you have 10 red pieces of candy and 36 total pieces, you would calculate the percentage as 10/36, which equals 0.27. Multiplied by 100, you get 27.7, and that’s your percentage of red candies: 27.7%
- Record your results in the corresponding table, then refer to the Normal Blood Count chart for different animals. Based on your totals, do you have a healthy level of blood cells for a cat? For a dog? For a cow?Tip: A cat has 6-20 white blood cells (x1000); a dog has 6-17; and a cow has 4-12.
Questions to deepen wonder and understanding.
- How does the immune system protect us against diseases?
- What diseases have you been vaccinated against?
- How can you better protect your pets or animals (if you have any) against diseases?
Investigate and Explore
Take what you've learned to the next level to learn more and explore the possibilities.
Humans have been studying blood for a long time. The invention of the compound microscope in 1590 made it all possible, and less than a century later the Dutch scientist Jan Swammerdam was the first person to observe red blood cells under the microscope, in 1658.
Over the centuries we’ve learned a lot about how the different kinds of blood cells drive the immune system, helping it to protect the body by fighting off illnesses. And science has progressed to help the immune system support itself with the evolution of medicines and vaccines.
Vaccines are injections that contain the same germs that cause a disease but have been weakened so they can’t make the body sick; instead, the immune system is stimulated to produce antibodies against the vaccine and, in turn, develops immunity against the disease the vaccine was created against.
The first vaccine was used in 1796 to provide protection against smallpox, but the story of vaccines began long before that. There’s evidence to suggest that the Chinese employed smallpox inoculation — not by vaccine, but by exposing a healthy person to a smallpox scab — as early as 1000 CE. Explore more about the history of vaccines here.
There are all kinds of diseases that used to be common that, thanks to vaccines, we don’t have to worry about anymore, including polio, measles, and smallpox.
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This work is supported by the Agriculture and Food Research Initiative, Education and Workforce Development Program, grant no. 2021-67037-33376/ Project Accession No. 1024940, from the U.S. Department of Agriculture, National Institute of Food and Agriculture.