Lesson 2 Plan

Assessing Risks to Society

Purpose:

This lesson will introduce students to the concept of risk -- how experts assess risk, how the public views risk, and how they sometimes differ. It will show how judgment is always a factor in assessing how risky an activity or technology is to people’s health and safety. Students will gain an appreciation for how difficult it is to achieve a common understanding of the actual risks involved when making societal decisions.

Concepts:

1. Every human activity involves some degree of risk.
   
   
2. Risk has many dimensions.
   
   
3. Scientists quantify relationships among risks by developing mathematical probabilities.
   
   
4. Judgment is an inevitable element in quantifying risk.
   
   
5. Someone has to make the decision of whether or not a level of risk is acceptable.
   
   
6. In making decisions about managing nuclear waste, officials must consider the quantifiable risks along with the public’s perception of the risks.
   
   
7. The most important aspect of the nuclear waste management program is to reduce the risks to people’s health and safety.
   

Duration of Lesson:

Two 50-minute class periods

Objectives:

After participating in this lesson, students will be able to

1. Discuss probabilities and risk assessment on an introductory level
   
   
2. Discuss the limitations of using probabilities in making societal decisions
   
   
3. Rank items in accordance with their perception of the degree of risk involved in each
   
   
4. Explain why they ranked the various items on the risk activity as they did
   
   
5. Compare their rankings with those of their classmates and those from a national survey
   
   
6. Speculate about why the rankings differ
   
   
7. Discuss risk and what can be done to reduce it in their own lives
   
   
8. Discuss both positive and negative results of risk management limitations

Skills:

Critical thinking, discussing, ranking given items, reading

Vocabulary:

Acceptable level of risk, probabilities, quantify, risk assessment, distribution of risk, judgment, risk assessment, risk management, risk perception

Materials:

Day 1
Reading Lesson: “Assessing Risks to Society”
Activity Sheet: Probability: “The Language of Risk Assessment”
Extra Credit: “Probability Exercises”

Day 2
Activity Sheet: “Risk”
Transparency: “Ordering of Perceived Risk”

Background Notes:

“The Debate about Risk”
“Perception and Judgment”

Day 1:
Probability: The Language of Risk Assessment

Suggested Procedure:

1. You may wish to begin this study of probabilities by discussing the definition of probability. It is important for students to understand that probabilities are simply that — probabilities — and offer no guarantees. Additionally, using probabilities has limitations.
   
   
2. Once students feel comfortable with the terminology, assign the reading lesson entitled “Assessing Risks to Society.” Allow approximately 15 minutes for reading.
   
   
3. Go over the instructions for the activity sheet entitled “Probability: the Language of Risk Assessment” and give students about 10 minutes to answer the questions.
   
   
4. Engage students in a discussion about the reading lesson and their answers on the student activity sheet (see discussion points below).
   
   
5. As a culminating exercise for this lesson, you may wish to have students write an essay on the function that risk assessment and probabilities serve in a technological society.

   (Risk assessment and the development of probabilities are a blend of the predictive power of the sciences [varies depending on the specific process] and analyses of human behavior. Probabilities attempt to bridge the gap between the sciences and the need for a decision-making tool in a technological society. The risks of a new or existing technology can be estimated and weighed against the benefits of that technology and the things the society values.)

For Class Discussion:

1. List a few ways in which you use probability or are affected by probability in your daily life.
   
   (Deciding whether to carry an umbrella, wear a coat, evacuate your home in the face of a hurricane warning, etc. If you drive a car, insurance companies use probabilities to determine insurance rates.)
   
   
2. Why are probabilities involving health and safety risks to humans more difficult to determine than those dealing with card games?
   
   (Probabilities involving health and safety risks to humans are more difficult to determine than many other types because a vast body of knowledge is often required before making predictions. With human beings, complex natural, societal, and technical factors are interrelated, and testing of the whole system is not feasible).
   
   
3. c) In many cases, regulatory agencies consider a hazardous substance, activity, or technology (e.g., new chemical, new flight pattern, new manufacturing plant) to be “safe” if the risk of serious harm to a typical member of the exposed population is no more than some established probability per given unit of time (often, per year). Worldwide, for example, the legally allowable risk of a premature cancer death in a population exposed to additional ionizing radiation ranges from 1 in 100,000/year to 1 in 1,000,000/ year. This refers to the risk of one premature cancer death per year among the most exposed persons. What do you think of this concept? Would you feel comfortable being a member of an exposed population if the risk of serious harm were 1 in 100,000 per year? Why or why not? What if the risk were 1 in 1,000,0000 per year? Why or why not? What are some complications or not-soobvious issues that regulators should consider?
   
   (Answers may vary; however, when discussing possible complications, you should look for students to mention such things as the difficulty in knowing the rate of cancer or accidental deaths in a population before introducing a new exposure, the everyday probability of health risks, the use of animals in laboratory experiments, and the fact that biological differences between the test population [laboratory animals] and the human population introduce some uncertainties.)
   
   
4. Think of some event you have heard of recently (through the newspaper, TV, radio, family, friends, teachers, etc.) that could have been predicted through use of probabilities. Explain or illustrate why you think this particular event could have been predicted.

Teacher Evaluation of Student Performance:

Participating in discussions and responding to reviews of readings will indicate a student’s level of comprehension.

Extra Credit:

For extra credit or homework, you may assign students one or more of the exercises on the activity sheet entitled “Probability Exercises.”

Day 2:
Risk Perception and Judgment¹

Note:

Participants in this study rated 30 activities, substances, and technologies according to the perceived risk of death from each. These people were asked to consider the risk (not just to themselves, but to anyone in society in general) of dying as a consequence of involvement with or exposure to the activity, substance, or technology being considered.

The four groups of participants were given 30 index cards upon which a particular activity, substance, or technology was written. They were told to study the 30 items individually, thinking of all the possible ways someone might die from each. The next step was to order the items from least to most risky and then assign a numerical risk value to each by giving a rating of 10 to the least risky and assigning the other ratings accordingly. Respondents were given additional suggestions, clarifications, and encouragement to do as accurate a job as possible..

The activity in which your students will engage has been modified to make it more appropriate for classroom use. The modifications will influence results. Student interest should be piqued by comparing their results to the results of the other groups mentioned above. It is important that they understand that their results have been influenced by the modifications made in order to adapt the activity for classroom use.

Students should also be aware that the table shown in the transparency is based on a very limited sampling. It might help to remind students that this study was conducted in 1976 and they should keep in mind, while comparing responses, that a great deal has happened and many things have changed since 1976. Societal and technical changes in the intervening years would probably have influenced the responses of the 1976 test groups, as they may the responses of your students. Discussing these potential shifts in responses among the groups might be a useful exercise in itself.

Suggested Procedure:

1. Pass out copies of the activity sheet entitled “Risk” and explain how this is the same questionnaire given to survey respondents as described in the note above. Go over the directions for the activity sheet and allow students approximately 15 minutes to complete the activity.
   
   
2. After students have completed the activity, ask them to list their two most risky choices and their two least risky choices and to write a few sentences explaining the rationale for their rankings.
   
   
3. Discuss students’ choices, asking which items they ranked high, which items they ranked low, and why. You may also want to ask students the following questions about the activity:
   
   
   • What do you think are the risks associated with the activities or technologies in the exercise? The benefits? What does the term “trade-off” mean? Why is the term “trade-off” often used in reference to risks and benefits of technologies?
     
     
   • What are the costs of reducing risk for the activities in this exercise? The benefits?
     
     (Do not limit your definition of cost to money; also consider such things as societal and environmental costs.)
     
     
4. Show students the transparency entitled “Ordering of Perceived Risk.” Ask students to compare their rankings with the rankings listed and to speculate about why their rankings may be different.
   
   
5. Ask the following questions pertaining to “Ordering of Perceived Risk”:
   
   
   • Which activities or technologies did all four groups rank about the same? Why do you think this happened?
     
     
   • Which activities did the four groups rank very differently? Why?
     
     
   • How do you think each group “measured” risk?
     
     
   • What do you think is the significance of the fact that the different groups ranked these items differently? Does this mean that the “experts” are right and the other groups are wrong?

   (You may wish to point out that, while both experts and laypersons assess risk by using judgments, the separate groups may consider different factors to be relevant. Perhaps students can better appreciate the last point if they are reminded that sometimes they and their parents have opinions that are divergent, at least in part because different factors are considered important.)

   • Is it important to understand that different groups see risk differently? Why?
     
     
   • How do you think we should deal with these differences in our democracy?
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   As part of this discussion, have students identify events that have occurred since 1976, when the groups were surveyed. These events may have influenced the students’ rankings. For example, because of the events of September 11, 2001, students may rank commercial aviation much riskier than those who took the survey in 1976. Similarly, the efforts of such public safety and crime victim groups as Mothers Against Drunk Driving (MADD), an organization founded in 1980, may have an influence on the responses of today’s students. Also, seatbelts were in most cars on the road in 1976, but air bags were not yet even an option. In regards to smoking, the most important dangers were common knowledge in 1976, but studies since then have established that passive exposure to someone else’s cigarette smoke can cause disease in a nonsmoker.
   
   
6. Engage students in a discussion about the risks in our lives and how to manage those risks (see discussion points below).
   
   
7. Have students write a short paragraph explaining the significance of this lesson to them.
   
   
8. In preparation for Lesson 3, have students read the section entitled “The Nuclear Waste Policy Act” as a homework assignment.

For Class Discussion:

1. What are some of the risks you face in your life? What could you do to reduce risk in your own life?
   
   
2. What should others do to reduce risk in our lives? Should all methods be used? What should the role of the government be?
   
   
3. Do you think some level of risk in our lives is acceptable? Why or why not?
   
   
4. How should decisions to determine levels of acceptable risk be made? What should the role of the government be?
   
   
5. Should everyone be made to reduce his or her personal risk in activities? Should there be penalties if people don’t? Are there examples in your life in which this occurs? Can you think of instances mentioned in the news? How do you feel about being forced to reduce particular risks in your life?
   
   
6. How has the development of technology affected risk?
   
   (Be sure to discuss both positive and negative effects.)
   
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7. How can we manage risk?
   
   (Generally, risk management involves providing for people’s safety by using safeguards in the design of a technology and by implementing laws, regulations, and procedures to assure safe operations. In addition, risk management involves striving for consensus in situations where people disagree about the level of risk associated with a technology.)
   
   
8. Explain the application of risk management to something you are familiar with, such as the automobile or sports. Does risk management guarantee absolute safety?
   
   (For automobiles students may identify traffic laws, auto and highway design, driving lessons, etc. For sports they may identify such things as rules, equipment, coaching, etc.)

Teacher Evaluation of Student Performance:

Participation in class discussion, completion of the activity sheet entitled “Risk,” and completion of the assigned paragraph explaining the significance of this lesson to them will indicate level of comprehension.

Enrichment:

“Factors Affecting Risk Judgements”

¹ The student activities, and some teacher notes, for the lessons on risk are based on information used by permission from “Facts and Fears: Understanding Perceived Risk” by P. Slovic, B. Fischoff, and S. Lichtenstein, in Societal Risk Assessment: How safe is Safe Enough, published by Plenum Publishing Corporation, New York, 1980.