Introducing Endangered Birds to Ulva, NZ -- Modeling exponential and logistic growth of the yellowhead population
In this Spreadsheet Across the Curriculum activity, students build an Excel spreadsheet to model exponential and logistic growth of a population, in this case an endangered species introduced to a remote island. First, the students use difference equations and generate graphs showing exponential growth of the population. They experiment with changing the variables and see from the results of the simulation that the population exceeds reasonable expectations of the number of birds the island can sustain. Then the students modify the model to include a carrying capacity, and they analyze graphs of the logistic model. "What-if" questions are emphasized throughout the activity.
- Use Excel to model exponential and logistic population growth.
- Make predictions about the effects of changing variables in the models.
- Test these predictions by doing numerical experiments with the spreadsheets.
- Develop Excel skills including entering equations, filling cells, and graphing.
- See the purpose and limitations of population models.
- Understand the relationship between algebraic equations and resulting graphs.
- Analyze the exponential and logistic curves.
- See how rates of change are represented in exponential and logistic curves.
Context for Use
Description and Teaching Materials
SSAC2007.QH352.BS1.2-stdnt (PowerPoint 1.4MB Aug4 07)
This module is a PowerPoint presentation with embedded spreadsheets. Students work though the presentation, answering questions and developing the spreadsheet. If the embedded spreadsheets are not visible, save the PowerPoint file to a disk and open it from there.
This PowerPoint file is the student version of the module. An instructor version is available by request. The instructor version includes the completed spreadsheet. Send your request to Len Vacher (firstname.lastname@example.org) by filling out and submitting the Instructor Module Request Form.
Teaching Notes and Tips
Note that there might be multiple correct answers for some of the pre-post test questions (Instructor version). In the first question, B could be logistic and a math student might know this. Also, the model examples might be arguable.
References and Resources
and Briskie, James V. 2006. Introduced Birds As Model Systems For The Conservation Of Endangered Native Birds. The Auk, Oct 2006