======Simulating Virus Transmission======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Viral Infection, Classroom Epidemic Demonstration
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====Summary====                   
{{$demo.summary}}



====Procedure====  
  - Number a set of culture tubes and pipets, one for each student.  
  - Randomly select one “carrier” tube and fill it with 5 mL sodium hydroxide solution. Fill the rest with 5 mL deionized water.  
  - Give each student a tube, pipet, and index card to record their exchanges.  
  - Students make three exchanges of solution with different partners, mixing after each exchange.  
  - After three rounds, add 2 drops of phenolphthalein to each tube. A pink color indicates infection; clear or yellow indicates no infection.  
  - As a class, record “negative” students on the board. Use the process of elimination and tracing of contacts to identify the original carrier.  
  - Conclude with discussion of how diseases spread and how epidemiologists trace infection sources.  




====Links==== 
The Red Plague - FlinnScientific: 
{{youtube>A-mcdBMImf0?}}\\

📄 Viral Infection! - Flinn Scientific: [[https://www.flinnsci.com/api/library/Download/2418b9c3705147c3b508efcf5383c8b8?srsltid=AfmBOoojIm0RAc8wSERLAA8M1NmLIpRI6aQq9uKDTLJ7_oTwegXS4nJ7]]\\

📄 Tracking a Virus - ncwit.org: [[https://www.teachengineering.org/activities/view/duk_virus_mary_act]]\\



====Variations====
  * Use paper cups instead of test tubes, and 'swap fluids' during a contact by pouring all of the solution into one cup then splitting it in half.
  * Vary the number of exchanges or initial carriers to change the infection rate.  
  * Use two carriers to simulate multiple outbreak sources.  
  * For smaller classes, reduce exchanges to two; for larger classes, increase to four.  
  * Compare how quickly infections spread when students only exchange within groups versus freely across the class.  




====Safety Precautions====
  * Sodium hydroxide is corrosive—wear goggles, gloves, and aprons.  
  * Students should never squirt or splash solutions.  
  * Clean spills immediately with damp paper towels.  
  * Wash hands thoroughly after the activity.




====Questions to Consider====
  * How realistic is this model compared to real viral transmission?  
  * Could you tell who the original carrier was before the indicator was added?  
  * How does increasing the number of exchanges affect infection rate?  
  * What difficulties arise when trying to trace the original source of an outbreak?  
  * How does this simulation relate to real-life epidemics such as influenza or HIV?  
  * Why are measures like isolation or limiting contact effective at slowing the spread of disease?