Topic: Disease Transmission.
 

Grade level: 9th grade
 

Time: One class period (40 minutes).
 

Instructional Objectives: Introduce students to viruses. Through the activity, the students will be aware of how diseases are transmitted.
 

Concepts Addressed: The activity will introduce students to viruses. Through the activity--students will be aware that diseases are transmitted by bodily fluids (blood, saliva).
 

Materials required: plastic cup, distilled water, phenolphthalein indicator, pipette and sodium hydroxide.
 

Engagement: Students are to provide an example of a disease. The teacher will then ask them how it is spread. If there is an outbreak of a disease, how is he original carrier determined. The Center of Disease Control (CDC) has this job. After doing the activity, the sudents will have to determine who the person is who was originally infected. Is it always possible?
 

Procedure: 1. Each student will be directd by the teacher to find another student to exchange fluids from their cups.
                  2. To exhange fluids, one person pours his or her liquid into the cup of the other person.
                  3. The person who receives the liquid then pours half of the liquid into the empty cup of the original person. Record the letter of the cup (each cup is marked with a letter (A-Z).
                  4. After the exchange has been made, return to your seat and record the name of the person with whom you exchanged fluids. Write it in table 1.

Table 1:

Contact 1	Contact 2	Contact 3
Student Name:

                  5. The teacher will then direct you to make another transfer. Repeat the same steps as in steps 2 and 3 with a different student.
                  6. After the exchange, return to seat and record the name of this peron in Table 1.
                  7. Repeat steps 2 and 3 with a different person. Then record in Table 1 the student's name.
                  8. The teacher will place a drop of phenolphthalein indicator (using the pipette) into each person's cup. Note the color change (if any).
                  9. If the fluid changes color (to pink) when in contact with the indicator, then the student has been "infected".
                 10. The teacher will then ask each student that has been "infected" to write the names of their contacts on the board.
                 11. The data will be copied into Table 2.
 

Table 2:

	Contacts
Infected Person	#1	#2	#3

                  12. Empty the cup into the sink and rinse with tap water.
 

Key discussion Questions:  Who was the original infected person? How do you know? What is the meaning of bodily fluids? How is the activity like the spread of a real infectiom? Name some diseases that are spread by bodily fluids.
 

Closure: Teacher mentions what was accomplished in the exercise. Students are asked if there were any questions. Students are then given an idea of what will be accomplished in the next lesson.

Assessment: Based on the quaity of the response to the questions, understanding can be obtained.
 

Extension Activities: Use a diagram of the student names to show the route of the infection in this class.