This lesson begins with a simulation of just how quickly an infectious disease can spread through a population, examines the spread of a sexually transmitted disease documented by the video "The Lost Children of Rockdale County," and ends with a survey of the role of the Centers for Disease Control and Prevention (CDC).
Estimated Time: 1 to 3 class periods of 90 minutes each (Dependent on discussion and analysis time)
Correlation to National Health Standards
Health Education Standard 1:
Health Education Standard 3:
* To make 100 ml of 0.1M sodium hydroxide, add 0.4 grams of sodium hydroxide to 100 ml of distilled water OR add 10 ml of 1.0 M solution of sodium hydroxide to 90 ml of distilled water.
1. Before students arrive in class, half-fill a clear plastic cup with water for each student in the class. To one of the cups, instead of water, add diluted sodium hydroxide solution. Provide each student with one cup of clear liquid and one empty cup.
Tell students that the class will be doing a little role playing to start off the day. They are going to pretend that they are all at a party and they are going to "make contact" with three other people at this party. But the rules for "making contact" are very specific. Explain these rules carefully, and quiz them for understanding before you begin.
2. Allow the students to "make contact" with three other students in the class. This will work best if movement is allowed and students interact with students from the other side of the class. Be sure they keep a list of with whom and in what order they made contact.
3. After the exchange has taken place, have students return to their seats, and announce that it is a week later, and the health department is concerned. Several students have contracted a disease, and all students who attended "the party" must be tested for this disease.
To determine if an individual has been "infected," a drop of phenolphthalein is added to each exchange cup. If the solution turns pink, the person in control of that cup is infected. If the color does not change, the student is not "infected." Depending on class size and how much "mingling" actually occurred, the results should be fairly dramatic, with twenty-five percent to possibly more than fifty percent of the class ending up infected.
4. Inform the class that only one infected person came to the party, and now it's time to try to determine who that was. Make a class chart on the blackboard or overhead as indicated below:
A "+" indicates a positive response (color change), a "-" indicates a negative (no change). Each student should be listed and then each of his or her contacts in order.
Eliminate the "un-infected" individuals and try to trace the transmission of the disease back to the original infected person. Once the class has guessed who started the disease, you can verify the results with a drop of phenolphthalein in the cups containing the original liquid.
5. Discuss the results or have students respond to written questions. Possible questions could include:
6. After discussion or collection of written responses, introduce "The Lost Children of Rockdale County" as a real-life story of the spread of a sexually transmitted disease that affected teenagers. Show the video from the beginning to 09:15. Have students take notes or answer specific questions about the video. Pause the video when it shows the chart constructed by the health department (approximately 05:40) and ask the students how the chart differs from the class's representation of its epidemic. Challenge the students to create their own diagram from the class data collected from the epidemic simulation. Possible questions to ask about the video include:
Have students research the various health organizations available in their own community. What local city, county or state health department services are available? Are there any private or not-for-profit agencies that focus on communicable diseases? How accessible to teens are these agencies or groups?