Carbon Footprint Exercise

Cinzia Cervato, Adam Sanford, and Karly Wortmann
Iowa State University
Author Profile


We designed a three-step assignment for students in introductory geoscience that asks them to calculate their carbon footprint during one specific week. The goal of the assignment is to increase student awareness of the various sources of energy consumption and of the impact that each one of them is having on the atmospheric carbon budget.

The assignment was implemented in fall 2008 at Iowa State University and students calculated their footprint during the week of Thanksgiving break. They submitted their calculations through an online survey system that allowed the instructor to download the data into a spreadsheet and create graphs comparing the footprints of the whole class. These results were shared with the class and we evaluated the impact of even small changes in a class with an enrollment of more than 500 students. As part of the assignment, students are also asked to write an essay where they reflect on their calculations and the impact they are having on the environment. Many students reported that they were not aware of the impact of 'secondary emissions' related to diet and found the assignment instructive.

Used this activity? Share your experiences and modifications



This assignment was administered through BlackBoard/WebCT to an introductory geology class of 500+ students. The only limitation for the size of the class is the free version of SurveyGizmo, which allows to retrieve data in tabular format for up to 250 submissions. Students can be divided into sections of no more than 250 students or the instructor can subscribe to the basic version with no response limit for $19 for one month.

Skills and concepts that students must have mastered

Basic math (multiplication and addition).

How the activity is situated in the course

The students collected data for this homework assignment during the week of Thanksgiving break, towards the end of the semester, and before we discussed about energy resources.


Content/concepts goals for this activity

The goal of this assignment is to make students aware of their own impact on the environment by having them calculate their carbon footprint for a specific period of time. The exercise includes basic math calculations and conversion of carbon dioxide to carbon, as well as a short essay that is graded. The results are downloaded, plotted in a histogram, and shared with the class to begin a discussion on energy consumption and human contributions to climate change.

Higher order thinking skills goals for this activity

Students calculate their own carbon footprint and compare it with national averages. Sharing with the class the results of the assignment allows us to place their own activities into a broader context and to address the question of how much can changes made by one individuals impact the environment. When the results are added up, it becomes obvious that even a small change can have a big impact if 500 people are involved in it.

Other skills goals for this activity

Students learn to convert from tons of carbon to carbon dioxide. Often values of carbon emissions are reported in the media without specifying if they refer to carbon or carbon dioxide. It is important that students understand the importance of units and the difference between carbon and carbon dioxide.

Description of the activity/assignment

Step 1. Students are asked to keep track of their energy use from a variety of sources (heating/cooling, electricity, transportation, secondary emissions, etc) during the 9 days of Thanksgiving break, when many of them are likely to travel. They use the total for the 9 days that they calculated using an online calculator to estimate their yearly footprint and compare it to US and world averages. For most of them, the amount of carbon emitted during those 9 days is quite large because of airplane travel or long-distance driving. However, using a week of break when many students will travel allows them to become aware of the significance of transportation in carbon emissions. We provided a table with electricity and heating/cooling bills for various residence halls for students who stay on campus during the break.

Step 2. Students complete an online survey where they are asked to enter the values that they have obtained for the various components of the calculator, perform some simple calculations and compare their annual footprint to the U.S. average. We used SurveyGizmo for the survey because it allows to download the data in a spreadsheet format and has some limited plotting features. The free version allows a maximum of 250 submissions, the Basic version ($19 per month, can be canceled at any time) has unlimited submissions.

Step 3. Students write an essay through BlackBoard/WebCT (Assignment). A few guiding questions are provided for this essay where students reflect on the results of their impact on the global carbon budget, what they found surprising, and if they plan to make any changes to their lifestyle to limit their impact. No length limit is set for the essay.

The guidelines and components of this assignment are available on a wiki page. The three steps can be implemented in BlackBoard/WebCT as a Lesson Plan with links to the online calculator (step 1), to the survey (step 2), and to the Assignment/essay (step 3).

Determining whether students have met the goals

More information about assessment tools and techniques.

Teaching materials and tips

Other Materials

Supporting references/URLs

The various components of the assignment are available at This wiki environment allows contributors to post comments and suggestions.

The online carbon footprint calculator can be found at

The assignment was put together by ISU undergraduate student Adam Sanford under the guidance of Cinzia Cervato (idea and content) and graduate student Karly Wortmann (technical implementation).