YELLOW FEVER: THE SCIENTIFIC METHOD IN ACTION
The Spanish-American War
 Soldiers stationed in _____________________ began to die in great
numbers ---- not from bullets.
 What was killing them was the disease known as
______________________________.
 At one point, more soldiers died from the disease than fighting in the
Spanish-American War.
Dr. Walter Reed
 The United States sent a commission to determine the _______________
of Yellow Fever.
 The commission was headed by __________________________.
What was the cause of Yellow Fever?
 Originally, it was thought that the disease was spread by coming in
____________________ with the infected person or through infected
materials such as bedsheets and clothing.
The “Cure”??????
 The clothing and bedsheets used by the infected soldiers would be
________________________ after use.
 They would also ____________________ the infected soldiers from the rest
of the troop.
 None of these measures worked!!!!!!!
Dr. Carlos Finlay
 A Cuban doctor who believed that Yellow Fever was spread by the bite of a
_______________________.
 At first, Dr. Reed did not agree, but he eventually devised an
______________________ to test this hypothesis.
Dr. Reed’s Experiment
 Dr. Reed and the commission assembled two groups of
______________________ for the experiment.
 One group would act as the ______________________ and the other the
______________________________.
The Control Group
 Wore the filthy _____________________ of Yellow Fever patients.
 Slept in the soiled ___________________ of Yellow Fever patients.
 Ate from the dirty ___________________ that Yellow Fever patients had
used.
 This was done for ___________________________.
 They were completed screened in and thus _____________________ from
mosquitoes.
The Experimental Group
 They used only ___________________ clothing, linens, and plates.
 They were ____________________ from Yellow Fever patients.
 They allowed themselves to be bitten by mosquitoes that had bitten Yellow
Fever patients.
The results of Dr. Reed’s experiment
 In the control group, _____________________ of the volunteers
contracted Yellow Fever.
 In the experimental group, ______________________ of the volunteers
contracted Yellow Fever and one died.
 This _____________________ that the mosquito was the cause of the
disease.
 As a result, war was declared on the mosquito and in ____ days, Havan was
free of Yellow Fever.
What could be the hypothesis for Dr. Reed’s experiment?
 That the bite of mosquitoes is what transmits Yellow Fever?
What is the variable in Dr. Reed’s experiment?
 Remember, a ____________________ is a single factor that is isolated and
tested in an experiment.
What is the main difference between the control and experimental groups?
 The control group ___________________ have the variable.
 The experimental group ___________________ have the variable.
Did Dr. Reed’s experiment support the hypothesis?
 YES!!!!