SISL > 2012 Sustainability in Math Workshop > Activities > How Big is Your Breakfast Footprint?

How Big is Your Breakfast Footprint?

Ben Galluzzo, Shippensburg University
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This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

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This page first made public: Apr 24, 2013


How does an individual calculate a carbon footprint? Can personal decisions alter the magnitude of a carbon footprint? How much does one person's carbon footprint really matter?

In this module students will explore the size, value and significance of personal carbon emissions. In particular, students will estimate the carbon footprint of a breakfast meal consisting of cereal, fresh berries, milk, and fruit juice. After comparing breakfast carbon emissions values with group members and the class, students will contextualize these results through analysis of the mathematical model, comparison with known carbon "sinks" and reflection on the meaning of the output.

Learning Goals

Many students are aware of the term "Carbon Footprint" but few know what one is. This activity allows them to develop perspective by viewing the term through the lens of a common daily activity, breakfast. When participating in this module, students will

  • Develop and analyze mathematical models
  • Find and evaluate data
  • Discuss the value and effect of decision making
  • Contextualize numerical results

This activity prepares students to effectively communicate about our societal challenges and potential solutions. The activity will

  • Advance students' literacy around sustainability issues
  • Encourage self-reflection and personal development of their "voice" for solving societal challenges
  • Promote creative visioning around sustainable futures

Context for Use

This activity is appropriate for introductory undergraduate mathematics courses (and appropriate high school mathematics courses) with less than 45 students; as students will work in groups of 3 or 4. For the 50-minute project described in the teacher notes, material needs include: calculators, access to the internet (preferred), collection of emptied breakfast menu containers (e.g., empty Kellog's Frosted Mini-Wheats box and empty strawberry "clamshell" container), and rulers. Students will take measurements, perform unit conversions and make calculations to answer questions on a provided worksheet. This module is appropriate for college algebra or introductory statistics courses early in the semester and appropriate at most any time for liberal studies math, quantitative reasoning, or basic math modeling classes. This module can be completed in a "stand alone" fashion or as a micro introduction to understanding the meaning and growth of carbon output on a national and/or global scale (see one example in "Breakfast Footprint Slides").

Description and Teaching Materials

  • Breakfast Footprint spreadsheet (Excel 2007 (.xlsx) 20kB Nov30 12) - An editable spreadsheet that can be altered to incorporate appropriate assumptions such as date, location, etc.; the page can then either be shared with students as a computer file or handout out as a worksheet to fill-in during class (preferred method, as it requires studenst to make calculations). An partially complete example used in a class at Shippensburg University is included.
  • Breakfast Footprint Slides (Acrobat (PDF) 1.6MB Nov30 12) - An example of how one could frame classroom activity and discussion. These slides were used in class at Shippensburg University.

Teaching Notes and Tips

Many students will not know how to start this problem if it is initially presented as an open-ended exercise and will lose interest if they believe the problem is too complicated to investigate. As a result, I recommend presenting the initial assumptions (i.e. transportation considerations, average fuel consumption, etc.) as "fixed" parameters for the problem. Wait to debate assumption choices after students have calculated their carbon footprint and have had time to discuss results (including "Analysis" questions) within small groups.

If it is possible to use a computer with spreadsheet software and shared access (e.g. computer at the front of the classroom), encourage each group to identify a "scribe" who will input all the team values to a spreadsheet at the front of the room. This allows for the quick calculation of a class average and a presentable graph of the distribution of classroom values. Comparisons should result in what appear to be very "small" numbers this should motivate discussion on the "is my result 'big'" question from the handout. In a 50-minute class period, there should be time for the instructor to provide some context in the form of trees (e.g., the trees on the campus quad); use the U.S. Department of Energy's "Method for Calculating Carbon Sequestration by Trees in Urban and Suburban Settings" (see resources for link) to determine the carbon sequestered by a pre-determined group of trees. In a longer class, students will have time to do the calculations independently.


After completing this exercise students are ready to begin to investigate "bigger" questions; both with respect to carbon output and mathematical modeling. A few suggestions for follow-up assignments are listed below.

Modeling: Students will have developed an understanding that a reported number is only as good as the model used to calculate it. Presenting students with a current news article that is based on a finding highlighted by a numerical result. Ask students to identify the assumptions that they believe should be included in the underlying model in order to make it believable.

Carbon Footprint: Have students calculate their average daily carbon footprint and compare this value with the average footprint of citizens from other countries across the world. Discuss the implications of their findings.

Modeling and Carbon Footprint: Classes investigating exponential and logrithmic functions will be prepared to develop and explore models on a global scale.

References and Resources

U.S. Department of Energy, "Method for Calculating Carbon Sequestration by Trees in Urban and Suburban Settings"
Use the tables on pages 7, 8, and 9 to calculuate carbon sequestered by identified trees.