Lesson 2The Pellagra Story

Key Vocabulary

• Ethics• Evidence• Hypothesis• Inference• Observation• Scientific Method• Trade-off

Although scientists use many methods to solve problems, scientists in the same field frequently usesimilar approaches. Often these involve doing an experiment.

For example, if a botanist (someone who studies plants) wanted to develop plants that resist drought, the botanist would use many plants and followprocedures common to many botanical experiments. A materials scientist working to develop a new type of plastic for an artificial limb would use a different procedure.

What kinds of experiments are possible when you study human beings?

How can you collect evidence in these situations?

Begin to consider these issues as you watch the storyof the disease called pellagra (puh-LAY-gra), which affected poor rural families of the South.

What are the common elements of all scientific problem- solving methods?

Materials

For each student• Student Sheet 1.1, “Anticipation Guide: Ideas about Experimental Design”

from Activity 1• 1 Student Sheet 2.2, “Observations and Inferences”• 1 Student Sheet 2.3, “The Pellagra Story: Dr. Goldberger and the Traditional

Scientific Method”

Copy the following questions to be answered during the video

• What was the problem of pellagra?

• What did people think caused pellagra?

• What evidence did Dr. Goldberger observe or collect about pellagra?

• What did Dr. Goldberger conclude about the cause of pellagra?

Procedure

1. To prepare to watch the story on the video, first readAnalysis Questions 1–4.

2. Your teacher will provide you with a student sheet or ask you to prepare a table like Table 1 to record your notes during the video.

3. Watch the story of Dr. Goldberger and pellagra on the video.

4. Complete Student Sheet 2.2, “Observations and Inferences.”

Dr. Joseph Goldberger

BeginPellagra Video

Analysis1. a. What was the first step in Dr. Goldberger’s research into pellagra?

Explain why this step was important in developing his hypothesis.

b. During this first step in his research, what evidence did Dr. Goldberger find that suggested that pellagra was not caused by germs?

2. a. What was Dr. Goldberger’s hypothesis about the cause of pellagra?

b. What did he do to provide evidence of the relationship between pellagra and nutrition? Be sure to explain how his research provided evidence that supported or disproved his hypothesis.

c. How could he have provided more convincing evidence of the relationship between pellagra and nutrition?

3. Why didn’t people believe Dr. Goldberger’s conclusion about the cause of pellagra? Give two reasons.

Analysis4. Compare the steps of the traditional scientific method to the steps Dr. Goldberger

followed to investigate pellagra. How were the steps the same? How were the steps different?

Traditional Scientific Method

Step 1. State the problem or question.

Step 2. Propose an explanation, also known as the hypothesis.Step 3. Collect evidence. (Conduct an experiment.)

Step 4. Analyze data.

Step 5. Draw conclusions, and, if necessary, revise and repeat the experiment.

Steps taken by Dr. Goldberger

Step1. (same) Why are only certain people getting the illness?Step 2. (same) hypothesized it is a disease linked to vitamin deficiency Step 3. (same) conducted an experiment at an orphanage and a controlled experiment of prisoners Step 4. (same) However, Goldberger assumed only poor people would

get ill due to improper diet.Step 5. (Different) conclusion incorrect. Why? Experiment not board enough, made assumptions, fail to seek specific cause.

Analysis5. Fill in the “After” column for Statements 3 and 4 only on Sheet 1.1, “Anticipation Guide: Ideas about Experimental Design.” Did your thinking change?

6. To investigate his hypothesis, Dr. Goldberger had prisoners volunteer to be fed a poor diet; as a result, 7 out of 11 prisoners developed pellagra. What do you think about Dr. Goldberger’s decision to experiment on people? Support your answer with evidence and identify the trade-offs of your decision.

Hint: To write a complete answer, first state your opinion. Provide two or more pieces of evidence that support your opinion. Then consider all sides of the issue and identify the trade-offs of your decision.

Remember: There is no wrong answer when asked your opinion

7. Reflection: How do people in different careers solve problems? Scientists, plumbers, engineers, auto mechanics, nurses, teachers, and many other workers solve problems. Choose two careers that interest you. Describe the kind of problems you think people face in these careers. Describe how you think they solve them.

What was the problem of pellagra?

-In 1914, pellagra was a common disease in the United States. It caused rashes,

insanity and death.

What did people think caused pellagra?

1. Eating corn

2. An insect

3. Bacteria/germs

4. Lack of nutrition/poor diet

What evidence did Dr. Goldberger observe or collect about pellagra?

-Pellagra was common in the South, particularly in poor areas and institutions (such as

mental hospitals, orphanages, and prisons).

-Many people in the South ate a poor diet, consisting of cornbread, fatback (pork), and

syrup.

-Staff at institutions (such as mental hospitals, orphanages, and prisons) did not have

pellagra.

-Orphans provided with fresh vegetables, meat, and milk either recovered from pellagra

or did not get it.

-Some prisoners fed a poor diet developed pellagra. When provided a better diet, they

recovered.

What did Dr. Goldberger conclude about the cause of pellagra?

-Dr. Goldberger concluded that pellagra was caused by a nutritional deficiency

(poor diet).

Key Vocabulary• Ethics

A system of principles that can guide decisions and practice in terms of whether something is morally right and just.

• EvidenceSomething that is helpful in forming a conclusion and is supported by data.

• HypothesisEducated guess

• InferenceA conclusion, or the process of developing a conclusion based onevidence.

• ObservationAny description or measurement gathered by the senses or instrument.Scientist collect evidence by making observations

Key Vocabulary

•Scientific Method A set of processes used when conducting an investigation

•Trade-off Potential outcome of any type of decision or action that involves some form of compromise, especially when each of the possible choices involves both advantages and disadvantages. When one option is chosen over another during a decision-making process, any desired outcome that must be given up is called a trade-off.