Cemetery secrets (2 of 2)
Lesson 7 of 16
Objective: Students will be able to 1) produce and analyze graphs using survivorship and mortality data; 2) make inferences about past and present human populations based on survivorship curves; and 3) describe the impact of advances in medicine and technology on human demography.
What data can we use to study human populations of the past? How can we model the survivorship rates of human populations? "Cemetery Secrets" is a variation of a popular demography lab in Advanced Placement Environmental Science courses. Students have just learned about how the human population has grown over time. Now they will investigate this population growth using data from the Brooklyn Greenwood Cemetery.
Specifically, students will develop survivorship curves for the human population data they gather and learn to apply the survivorship framework to different populations. For background, there are three types of survivorship curves. Here is a diagram that captures all three:
There are three types of survivorship curves. The type I curve shows species where most of the young survive until old age. The type II curve is for species that have relatively constant mortality at every age. (There is no dramatic increase in the number of deaths in advanced age as with Type I). Finally, the type III curve is a model for species that have high mortality in the youngest age groups and low mortality after that. Humans are generally type 1, but the survivorship curves for humans will vary among different groups.
During the first lesson of "Cemetery Secrets" students will consider the local Greenwood Cemetery as a rich data archive, define demography through a short text reading, and begin to collect virtual data from Greenwood cemetery.
During the second lesson, students will learn about the survivorship curve model, graph collected data from Greenwood as a survivorship curve, and apply the survivorship concept to analysis of various human population.
By the end of this lesson sequence, successful students will have met the following objectives:
- define demography
- collect lifespan data from an internet database
- produce and analyze graphs using survivorship and mortality data
- make inferences about past and present human populations based on survivorship curves
- describe the impact of advances in medicine and technology on human demography.
HUMAN DEMOGRAPHY SEQUENCING NOTE: For an overview of what students will learn about human demography and how this learning builds towards the CAPSTONE for this unit, see the outline below:
7 Billion : Students learn about factors that have influenced the growth of the human population over time.
Focus question: How has the human population grown so large so quickly?
Cemetery secrets: Students learn that modeling the survivorship of different human societies reveals that human demography data is heterogeneous. The "human population" is actually many human populations, separated by geography and time.
- What data can we use to study populations of the past?
- How can we model the death rate of a population?
Human Population Pyramids: Students learn how to develop the population pyramid data visualization tool to formally represent an analyze the various human populations throughout the world. In this process, students develop an evidence-based understanding of how different population structures uniquely impact the Earth and how these unique impacts will become more or less intense over time.
- How can we represent the essential demographic data of a human population using an elegant data visualization tool?
- What demographic information does the shape of a population pyramid reveal and how does this shape predict future a population' future growth?
- How might the population pyramids of countries be used to develop public policy?
Demographic Transition: Students learn about a model of how population change over time and use this model to describe how human populations will impact the Earth in the future.
Focus question: How do different rates of development within a country influence how specific human populations will impact the environment?
RESOURCE NOTE: The attached PROTOTYPE ACTIVITY GUIDE contains a series of learning activities that might be modified by educators for classroom use.
ATTRIBUTION NOTE: Some activities were modified from materials found on The Biology Corner.
PRIOR KNOWLEDGE NOTE: Students will be most successful in this lesson if they have had experience constructing survivorship curves. See the REFLECTION to this FRAME for a lesson idea for building students' ability to construct these curves.
What is the purpose of this activity?
In this FLIPPED assignment to be complete before class, students will learn about the survivorship rates of a model species (oysters) and then watch a tutorial of survivorship curve construction. By the end of this activity, students should be able to accurately explain the differences among type I, II, and III survivorship curves and should understand the general framework for constructing curves.
What will students do?
First, students learn about how to construct a survivorship curve for oysters, a type III model organism that students have previously studied. Describe the shape of the survivorship curve for oysters. Then, in a short paragraph, explain the information this curve conveys about oyster populations.
Second, students learn about how to construct survivorship curves. Describe the process of creating a survivorship curve? What labels go on the x and y axis? What information do you need to create a curve? Which curve models human survivorship? Explain the information the curve describing human survivorship conveys about human populations. NOTE: It is not necessary to understand the difference between r and k species.
RESOURCE NOTE: The attached video files are duplicates of the embedded videos. They are attached in case youtube access is blocked.
What is the purpose of this section?
Students will continue their work from DATA LAB 1 as they graph and analyze data collected from Greenwood Cemetery. By the end of this section, students will have constructed a survivorship curve from collected data and compared this curve to curves constructed by other groups in the class.
What will students do?
Students will continue to follow the "Data Digging" protocol to extract human demography information through a Greenwood Cemetery virtual visit. This protocol will continue to be done in teams so that students have the opportunity to collaborate with other students and troubleshoot problems together. The first three steps were completed during the prior lesson. The last two steps are the focus of DATA LAB 2. Here are all of the steps:
- develop hypotheses
- visit Greenwood Cemetery or an online database to record dates of births and deaths etched on the headstones
- examine demographic parameters such as survivorship and mortality of males and females during two time intervals: deaths pre-1950 or post-1950
- create graphs of the data
- compare the data and suggest some causes for the results
Before developing survivorship curves, the small groups engage in a short discussion of the process of creating survivorship curves and the meaning of the resultant curves. Groups have three guiding questions:
- How do we create a survivorship curve? What labels go on the axis? How do we plot points?
- What are the three types of survivorship curves? What does each type of curve communication about a population?
- What is confusing about this process?
As groups discuss, the teacher will circulate to check for student understanding. Once groups have finished (three to five minutes) each group shares out responses to question three. This is "confusion data" is valuable because it allows the teacher will to better understand the needs of different groups.
Step 4-Create graphs of the data
The PROTOTYPE ACTIVITY GUIDE contains a blank graphing space for students to use to construct a survivorship curve from the collected data. To simplify curve creation, students will not use a log scale. Rather, on the y axis students will use "percent of individuals surviving"; on the x axis students will use "time in years." For these graphs, the largest value on the x axis was 120. This value captured all life spans for collected data. This setup is captured in the annotated image in the RESOURCES section as well as the model survivorship curves from the FRAME. Students will plot the point for percent of individuals surviving at the end of each age range (on the "9s"). Most students will have seven to 10 data points.
Step 5-Compare the data and suggest some causes for the results
Once students have graphed the survivorship curve for their collected data they transcribe the survivorship curves constructed by other groups onto their activity guide. Each data set should have its own line (one line for females who died before 1950, one line for females who died after 1950, one line for males who died before 1950, and a line for males who died after 1950.)
Finally, students compared the four constructed survivorship curves and develop explanations for any differences observed.
What will teachers do?
Students will need to have completed the data table before constructing survivorship curves. However, even with a completed data table, students are most likely to struggle with identifying the parts of the data table that will be used. Teachers should model the plotting the first data point using the first and last columns of the data table if students need additional support.
Students may also struggle with the analysis of the collected curves. If students struggles, teachers should suggest that students revisit the framework developed in "7 Billion." Are any of the factors that impacted human populations throughout history relevant to the four groups in this lab?
EVALUATE: Problem set
What is the purpose of this section?
Students test their undestanding of survivorship curves through a problem set in order to identify areas of proficiency. By the end of this section, students should have demonstrated the ability to make inferences about populations based on survivorship curves and also suggest causes of different survivorship curves from human populations.
What will students do?
Students work through a series of self-paced problems.
The first two problems are interpretation questions. Can students accurately compare the survivorship curves of different populations and provide accurate evidence for observed differences? Students that are able to answer these questions will identify specific factors, such as the development of medicine or armed service, as most likely responsible for differences among groups.
3. In Africa, AIDS takes its toll on the population, but deaths occur most frequently in the 20-40 age group. Show a survivorship curve that would illustrate this pattern.
4. What shifts in survivorship and mortality curves would you expect if significant cuts were made in social services such as prenatal and infant care?The fifth and sixth problems ask students to evaluate the quality of life in a human population based on the information in a survivorship curve. Do students understand that high death rates in early life are indicate of an underdeveloped medical infrastructure? Can students explain why gathering information about survivorship is valuable? Students able to answer these questions will be able to identify factors that influence the shape of survivorship curves and will also be able to explain that survivorship curves are essentially profiles of human populations that provide important information about the needs of those populations.
5. Compare the two curves below: Which country is probably the better place to live? Defend your answer.
6. Give specific examples of the types of information that human survivorship curves and age
structure diagrams reveal for different cultures. Discuss, using examples, why this type of data collection and analysis is valuable to a culture/country in the long term.