Population Ecology

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Objective

Students will examine the relationship between population change and environmental conditions.

Big Idea

How fast a population grows is determined by the amount of resources available.

Warm-Up

5 minutes

Warm-up: What factors do you think contribute to the increasing growth rate of the human population?

This question is a great way to activate thinking for the lesson.  Allow students to share their thoughts with the class for 1-2 minutes.  Listen and list their ideas on the board.   Listen for students’ critical thinking and ability to build off one another’s thoughts and comments.  If the group struggles with this question, ask probing questions like, “Why do you think people live longer now?” to help get them thinking.  

Introduce New Material

20 minutes

Begin the lesson with a video, 7 Billion: How did we get so big so fast?  This is a brief and visually stimulating video that uses an image of a water glass to summarize population growth and factors that affect it.  

Allow students to share their thoughts and reactions to the video for 1-2 minutes before introducing the vocabulary associated with the lesson: emigration, immigration, birth rate, death rate, exponential growth, logistic growth, linear growth curve, boom or bust curve, survivorship curve, and carrying capacity.

Say each word aloud and ask students to repeat the term after you.  Clap out the syllables for the terms with 3 or more syllables.  This helps students hear the word parts of more complex words so that they can pronounce them correctly.  Provide explicit instruction of each term when it arises during the course of instruction. Surprisingly many students do not associate the term boom with an increase in growth, rather a decrease  in growth based on their interpretation that it somehow involves a bomb which would lead to lost lives. 

Inform students of the learning targets for this lesson:

  • I understand factors that affect changes in populations.
  • I can interpret graphs to understand growth rates and identify growth curves.
  • I can use data to create a visual display that informs.

Display visual information as you instruct and ensure students take notes using guided notes that you provide or use a note-taking strategy that you have taught. Because the lesson is brief, I instruct students to take note using the Cornell notes format that has been taught.

Spend time discussing the factors that influence the growth of a population: immigration, emigration, birth rate and death rate.  A good way to help students remember the difference between immigration and emigration is to point out emigration begins with the letter “e” like the word exit and immigration begins with the letter “I’ like the word inside. Discuss and display each of the 3 growth patterns of population growth.  Encourage students to create their own word associations to help them learn the differences between the growth curves.  For example:

  • The logistic growth cruve is "S" shaped so associate the shape of the curve with the letter "s" in the word logistic.
  • The linear growth cirve is a line so notice the word "line" in linear.

As a check for understanding, use visual images to assess how well students are able to identify each type of growth curve.

End with a discussion of the epidemiologist careerShow a brief video clip that allows student to see the role of an epidemiologist.

Encourage students to conduct their own research into the field of epidemiology if they are interested.  

Guided Practice

5 minutes

Inform students that they will practice some of the work of an epidemiologist and use real data to create survivorship curves using obituaries to determine the trend for Type I survivors for the data they collected.

Display the Survivorship Curves Lab and distribute copies to students.  Identify the problem question that they will answer. Summarize the procedure and explain that students will collect data on 35 individuals.

Model how to identify number of deaths by age from the obituaries and record the data in the table.  Explain that the age groups in the table should be 5-year groups, extending from 0-5 through 90-95.  Model how to create the first 3 groups, 0-5, 6-10, 11-15, etc…

Explain that students will read the obituaries and make tally marks in the table for deaths in each 5-year age group.  Model how students will calculate number of survivors (35- number of deaths in the age band) and survivorship rates (# survivors/35 x 100).

 

EXAMPLE:

 

AGE(YEARS)

DEATHS

SURVIVORS

% SURVIVORS

0-5

I

35-1=34

97

6-10

I

34-1=33

94

11-15

0

33-0=33

94

16-20

IIII

33-4=29

83

ETC…

I

29-1=28

80

 

 Model how students will graph the data by plotting the age group on the x-axis and the percent survivors on the y-axis.

Discuss how students will need to give an explanation for all trends that are identified.


Independent Practice

20 minutes

Distribute graph paper, obituaries, and calculators.  Check for understanding by asking students to summarize each of the steps of the lab procedure, to ensure that everyone is clear on what to do:

  1. Obtain the obituary section of the newspaper.
  2. Create a data table like the one on the lab procedure that extends to include five-year age groups up to 90-95 years.
  3. For 35 obituaries, place a tally mark next to the age group in which the individual died.
  4. Subtract the number of individuals that died from the number of remaining survivors and record the answer in the column of your data table.  Calculate the percent surviving in each age group by dividing the number of survivors by 35 and multiplying by 100.   Repeat this step for all age groups.

If students are not able to delineate the steps, go back and review all parts of the lab procedure before releasing students to work independently.  If students are unclear about the lab procedure, the added time for review will eliminate a lot of headaches later.  

Walk around and provide assistance as needed to students. Listen and observe students as they work.  It is likely that some will require help with the calculations.  It might be helpful to provide small calculators for students to use or allow them to use their phones.

The student work sample shows that the student was able to not only complete the calculation, but also graph the data correctly.  The student was then able to interpret the data to draw a reasonable conclusion about human death rate.

Close

5 minutes

Engage students in a discussion around this question:

What type of actions, if any, should we be taking to address the population growth concerns? 

Activate students’ thinking by mentioning factors that affect carrying capacity, like food.  Allow students to share their thoughts with the class.  Look for students to identify alternative food sources and different ways to use consumable resources as ideas.