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The Spread of Disease
P.E. & Health, Science
9, 12, 11, 10
Title – The Spread of Disease
By – Tom Kuntzleman
Primary Subject – Health / Physical Education
Secondary Subjects – Science
Grade Level – 9-12
- One clear plastic cup for each student.
- Safety goggles for each student.
- Gloves for students may not be a bad idea.
- About 2 Liters of 0.3 M sodium hydroxide (dissolve 26.6 grams of NaOH in 2 Liter of COLD water).
Be very careful doing this, the solution may get very hot!! Sodium hydroxide can cause severe burns. If you spill any on yourself, rinse first with vinegar and then with plenty of cool water. Red Devil Lye, which can be bought in many grocery stores, is essentially sodium hydroxide. Sodium hydroxide may also be purchased from any science supply. If you are a Health/P.E. person interested in doing this lesson, check with chemistry/science instructors in your building because they may have some sodium hydroxide.
- A solution of phenolphthalein indicator (sold by any science supply). Again, it may be helpful to check with chemistry/science instructors in your building for some phenolphthalein.
- Overhead projector.
- Medicine dropper.
- Plenty of water.
- Vinegar (for safety purposes)
WARNING: UNDER NO CIRCUMSTANCE SHOULD STUDENTS BE ALLOWED TO DRINK THE CONTENTS OF THE CUPS. FURTHERMORE, IF THE CONTENTS OF THE CUPS ARE SPILLED, THE AREA SHOULD BE IMMEDIATELY BE FLUSHED WITH VINEGAR AND THEN PLENTY OF COOL WATER. SAFETY GOGGLES SHOULD BE WORN AT ALL TIMES AND ALL SPILLS SHOULD BE REPORTED TO THE TEACHER. SPECIAL CARE SHOULD BE TAKEN BY THE STUDENTS TO PREVENT SPILLING THE CONTENTS OF THE CUPS ON EACH OTHER AND THE SURROUNDING AREA.
- Pour a small amount of water (about 50 mLs) into each plastic cup except for one. In this last cup, pour 50 mLs of the 0.3 M sodium hydroxide. Do not let the students see you prepare the separate cups. It is a good idea to prepare enough cups for 3-4 different mixing opportunities. When you are ready to begin the activity, hand out a cup of water to each student, but be sure to give out the cup filled with 50 mL of sodium hydroxide to one (it can be more than one if you wish) student as well. It is a good idea for you to make a mental note of which student received the sodium hydroxide, as most students will want to know who had the “disease”. Do not let any students know who has the cup with the sodium hydroxide. Explain to the students that they are going to simulate the spread of AIDS (or any other disease). Explain to the students that one person in the classroom has AIDS (the student with the cup full of sodium hydroxide). Tell the students that the virus is spread if and only if two people share the contents of their cups (by mixing). Tell the students that they will have the opportunity to mix their cups with each other for about five minutes, but they may also choose to refrain from mixing.
- Give the students ample time to mix, back and forth, the contents of their cups with each other. After this time (2-5 minutes should be plenty), have the students take their cups with them back to their seats. After the students have settled down, turn on the overhead projector. Have the students place their cups on the overhead projector and focus the projector such that the entire class can observe the liquid that is inside the cup is clearly projected onto a screen or white wall. Add 1-2 drops of the phenolphthalein solution. If the liquid turns pink, the student has caught the virus! If the liquid stays clear, the student is healthy!
- A whole host of modifications can be done on this lesson. For example, what is the effect of allowed mixing time on the spread of the virus? What effect does abstinence have on the spread of the virus? What if only everyone mixes with only one person? Can anyone think of a method of “safe mixing”? Each new question should be tested with a new mixing run.