Often we live lives of contradictions. We demand zero risk from pesticide residues on fruits and vegetables or from `second-hand' cigarette smoke, but take a large risk quite voluntarily when we don't fasten the seat belt in our car.
How are the risks of activities assessed? How do we decide whether a risk is unacceptable? How do we determine what risks are present? This unit gives students a chance to consider these questions in the context of issues and events important in their lives and the lives of those around them.
This unit is based on two key resources: Risk Comparison and Determining Threshold Limits. If you are going to use the model unit, you will need one copy of each of these modules. The activities selected from these modules and from the Suggested Activities section of this Guide present the concepts of science in the context of their application in society and their implications for society.
The activities utilize a variety of instructional methods. Suggestions for evaluation strategies accompany the lessons, and can be incorporated into an overall evaluation plan for the unit and the year. When moving away from a `text for each student' model of science education, as this unit does, two things are especially important. One is that the evaluation techniques used must complement the instructional methods. For example, to use at the end of this model unit a single exam with questions stressing only ability to recall information as the sole evaluation technique would be a mismatch between the instruction and evaluation. To use such an exam in combination with several or many of the strategies suggested in the lesson outlines, and to add questions involving application, analysis, or evaluation to the exam would be a more valid assessment of student abilities.
While Indian and Métis curriculum perspectives and concerns of Gender Equity have been included while writing this unit, look for ways that more sensitivity to these important principles can be expressed in your classroom.
Materials
Books (See Key Resource Correlations for citations.)
Video (see citation in the reference list on page 102)
This schedule is based on 45 minute class periods.
| Lesson | # of periods |
|---|---|
| 1 | 3-4 |
| 2 | 1 |
| 3 | 2-3 |
| 4 | 2 |
| 5 | 1 |
| 6 | 1 |
| 7 | 3 |
| 8 | 3-4 |
| 9 | 2 |
Ideas for continuous assessment are outlined with each lesson overview. The information from these activities would be combined with a unit end examination. Questions for this exam would be drawn from the evaluation sections on pages 45 to 47 of Determining Threshold Limits and pages 43 to 44 of Risk Comparison, from the discussion questions that accompany the activities in these modules, and from questions raised and considered in class.
Factors of scientific literacy
1.1 Understand and demonstrate the concepts of probability and chance.
Resources
Assessment
The questions from this section can also be used as models for questions on a unit exam.
If there are objections to using a die in the classroom, a toque or hat containing marbles of six different colours could be substituted for the die. Mix by shaking, draw a marble, record the colour, replace the marble and repeat. A key can be used to convert data from colours to numbers if you want to use the data for calculations. (For example red=1, green=2, and so on.)
Create a game based on the use of this spinner. Experiment with altering the spinner to make it biased.
Discuss the difference between independent events based on pure probability (whether a flipped coin comes up heads or tails) and dependent events that involve probability, such as in rock - paper - scissors outcomes.
Factors of scientific literacy
1.2 Relate the concept of probability to the concept of risk. 1.3 Compare risks of various voluntary and involuntary activities.
3.3 Explore how moral values influence behaviour and assessment of risk and benefit.
3.4 Recognize the importance of fact-finding, prior experience, and open dialogue in the development of reasoned arguments.
Materials
Assessment
Activities
Lesson 3
Factors of scientific literacy
Objectives
1.2 Relate the concept of probability to the concept of risk.
1.3 Compare risks of various voluntary and involuntary activities.
2.1 Consider how risk is assessed.
2.4 Discuss how the value one places on an activity influences the amount of risk one is willing to accept.
3.4 Recognize the importance of fact-finding, prior experience and open dialogue in the development of reasoned arguments.
Resources
assessment
write a paragraph on the topic "There is no such thing as a risk-free life." A good paragraph will:
Distribute the Risk data sheet. Calculate the numerical risk per 100 000 persons, using the statistics canada data given. Rank the hazards according to the risk as expressed by this number. Compare this ranking with the rankings done in the first part of this activity.
Why isn't the estimated population at risk the same value for each risk listed?
Heart disease is a lower risk for the 10-19 year age group than for the population as a whole. What other event or activities might pose a lower risk for this age group? Which might pose a higher risk? Be prepared to give reasons to support your statement.
Discuss the reasons for the variations which show up in the Risk chart. Suppose that the numerical risk of injury from jumping from a car moving at 30 kph is expressed as 50 000 in 100 000. Express that risk as a probability for each person jumping from the car.
Numerical risks that are expressed in the form "1 chance in 2" are called risk probabilities. They can be calculated from the numerical risk data. Calculate risk probabilities to fill in the Risk Probability chart, using data from the Numerical Risk chart. Several cells are completed for you to be able to check your method of calculation.
The injuries to these people were categorized as minor, moderate, or major. Of those injuries to people wearing seatbelts, 1 750 were minor, 2 824 were moderate, and 479 were major. Of those injuries to people not wearing seatbelts, 214 were described as minor, 549 as moderate, and 307 as major. Present this data in a table showing both absolute numbers of casualties and the risk probability statistics for each group of people.
Write a paragraph summarizing your conclusions and recommendations from analysis of this data.
Then compare the costs and benefits of an involuntary activity such as the risk of homicide. How can the number and relative worth of the costs and benefits be changed?
Factors of scientific literacy
Objectives
1.3 Compare risks of various voluntary and involuntary activities.
2.1 Consider how risk is assessed.
2.4 Discuss how the value one places on an activity influences the amount of risk one is willing to accept.
3.2 Understand the potential narrowness in adopting a single perspective in judging the impact or influence of objects, experiences or events.
3.3 Explore how moral values influence behaviour and assessment of risk and benefit.
3.5 Establish arguments based upon human rights, human needs or needs of the environment when examining social issues.
Resources
Questions 1-9 may be adapted as items for a unit test, as may the swine flu story, and questions presented in the "Going Further" section on pages 23 and 24. Alternatively, the swine flu example may be given to students (as individuals or groups) as a homework assignment.
Factors of scientific literacy
Objectives
2.1 Consider how risk is assessed.
2.2 Assess significance of contaminants in water supplies.
3.1 Understand the natural environment and the conditions
putting it at risk.
3.4 Recognize the importance of fact-finding, prior experience, and open dialogue in the development of reasoned arguments.
Resources
Assessment
Factors of scientific literacy
Objectives
2.2 Assess significance of contaminants in water supplies.
3.4 Recognize the importance of fact-finding, prior experience and open dialogue in the development of reasoned arguments.
Resources
Suppose that in a test to determine the threshold of taste sensitivty to grapefruit juice, 6 people reported that they could detect it at a dilution of 1 part grapefruit juice in 8 parts water, two reported that they could detect the taste at a dilution of 1 part grapefruit juice in 10 parts water, and one person reported detecting the taste when it was diluted to 1 part grapefruit juice in 12 parts water.
a) Draw a bar graph showing the data collected.
b) Write a general statement about the outcome of this test.
c) What factors or conditions might influence the outcome of this
test?
This is a rare activity in that it asks students to taste salt solutions to experience the concept of threshold limits of detection.
Make sure that all droppers and beakers used in this activity are absolutely clean. It would be a good idea to use a new box of droppers and some drinking glasses for the solutions each time this activity is repeated. Instructions for making the salt solutions are found on page 53 of the module. Pickling salt (non-iodized sodium chloride) can be used instead of reagent grade sodium chloride.
Factors of scientific literacy
Objectives
2.2 Assess significance of contaminants in water supplies.
3.4 Recognize the importance of fact-finding, prior experience, and open dialogue in the development of reasoned arguments.
Resources
Since this is an activity involving active investigations, it is ideally suited for performance assessment. After the activity, stations can be set up where students individually or in groups go to investigate a different system (calcium chloride, sodium carbonate, potassium chloride) that produces a precipitate. Alternatively the activity outlined on Student Sheet 2.3 could be used as a performance assessment instrument if not used during this lesson.
Checklists such as the one on page 74 of Student Evaluation: A Teacher Handbook can be adapted for use with this activity. Another model of a checklist is found in this guide, as are sheets for use in self-assessment.
(From 5 to 6 mL of the silver nitrate solution, about 1 mL of the potassium chromate solution and 0.5 mL of the phenolphthalein solution will be needed for each group to do Activities 2 through 5.)
Factors of scientific literacy
Objectives
2.3 Recognize how scientists estimate toxicity levels from experimental data.
2.4 Discuss how the value one places on an activity influences the amount of risk one is willing to accept.
3.1 Understand the natural environment and the conditions putting it at risk.
3.2 Understand the potential narrowness in adopting a single perspective in judging the impact or influence of objects, experiences or events.
3.3 Explore how moral values influence behaviour and assessment of risk and benefit.
Resources
The evaluation section on pages 45 to 47 has a number of multiple choice and open-ended questions that could be used as is or as models for questions you develop. Questions 4 and 13 are examples of multiple choice questions that require an application of knowledge.
Factors of scientific literacy
2.3 Recognize how scientists estimate toxicity levels from experimental data.
2.4 Discuss how the value one places on an activity influences the amount of risk one is willing to accept.
3.3 Explore how moral values influence behaviour and assessment of risk and benefit.
3.5 Establish arguments based upon human rights, human needs or needs of the environment when examining social issues.
Resources
Activities