Carbon Footprint of Food Lesson
Lesson Plan
55 minutesGrades6, 7, 8Mathematics
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Written by Dan Castrigano
About this lesson
In this lesson, students use real greenhouse gas emissions data to compare the environmental impact of different foods through rate and ratio calculations. Students practice proportional thinking in a real-world context, connecting math skills to everyday food choices and climate change.
Inquire: Students explore an interactive data tool showing the environmental resources required to produce different foods.
Investigate: Students select pairs of foods, record their emissions data, and complete a series of rates and ratios to compare environmental impacts.
Inspire: Students discuss what their calculations reveal about food and the environment, then reflect as a group on what they learned and what surprised them.
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Everything you need to teach it
How to edit these materials (video)Teaching tips
Suggestions
- This lesson can be taught during a ratios and proportional reasoning unit as an applied, real-world context for skills building. It works best after students have been introduced to ratio language but before they have had much practice applying it to complex problems.
- Encourage groups to choose food pairs that feel personally relevant or surprising.
- This lesson shows the great disparity between certain types of foods. For example, creating 1 kg of beef from a beef herd emits 99.48 kgCO2eq. Creating 1 kg of potatoes creates only 0.46 kgCO2eq. Raising beef creates more than 200 times the carbon dioxide as raising the same amount of potatoes.
- Teachers should be mindful of their classroom context and students' relationships with food. Some students may come from homes where access to a variety of foods is limited or where food choices are determined by family, culture, or economic circumstances.
- Teachers should frame the lesson around systems and data rather than individual food choices; for example, asking “What does the data show us about how food is produced?" instead of saying "You should eat less beef."
- Consider inviting a local farmer or agricultural professional to speak about how food is grown or raised in your region, what resources go into production, and how they think about environmental impact in their own work.
- A registered dietitian or school nutritionist would make a strong guest speaker for connecting the environmental data to health and nutrition.
- Consider connecting with a local food bank or food access organization as an extension to explore how food insecurity shapes food choices in their own community.
- Check out these other SubjectToClimate lessons and units exploring food and climate:
- Food & Climate Change Unit: 6 lessons, ELA, social studies, and economics
- The Arctic: Food Security Lesson
- Food Waste Lesson
Prerequisites
- Teachers will need to share the Student Slideshow with students and grant them editing rights. They will all be writing in the same slideshow.
- Students should be comfortable multiplying and dividing multi-digit decimals, since the kgCO₂eq values in the data require decimal operations throughout the Investigate section.
- Some familiarity with greenhouse gases and climate change at a basic level is helpful, but not required
- Kilograms are used in this lesson. Some students will be unfamiliar with this unit. You can read more about the kilogram at Britannica. An easy conversion from kilograms to pounds is 1 kg = 2.2 lbs.
- Kilograms of CO2 equivalent are also used in this lesson. To make this more concrete, have students imagine holding a 2.2-pound ball in their hands. This ball has mass and takes up space. This is the "pollution" generated when creating different foods.
- Teachers can work through the example food pair calculations in the speaker notes before class to anticipate where students will get stuck.
Differentiation
- Teachers can create groups of students with mixed abilities.
- Teachers can pre-select food pairs for groups, focusing on pairs with a large and obvious emissions difference (e.g., beef and rice) so the ratio is easier to interpret.
- Teachers can provide a step-by-step calculation guide with sentence frames: "The ratio of ___ to ___ is:. This means that for every 1 kg of ___, ___ kg of CO₂ is produced."
- Allow struggling students to use a calculator for decimal operations so the focus stays on ratio reasoning rather than arithmetic.
- If a group finishes early, students can work on these extension questions:
- Food 1’s emissions are what % of food 2’s emissions?
- Can you convert your answers from kilograms to pounds?
- The Investigate section features a completed table of calculations. You can use this before the students begin their calculations. You can also share this with certain students or groups and let other groups complete their calculations on their own. Another option is to have students use the completed table to check their thinking when they are finished. There is a walkthrough of calculations in the speaker notes of this slide.
- Students can calculate across all three of their food pairs and identify which pair had the greatest disparity, then explain in writing why that matters environmentally.
- Students can design their own "most sustainable meal" using the data explorer, calculate its total emissions, and compare it to a typical meal of their choice.
- Students can research why a specific food has high or low emissions and present their findings to the class.
From the scientist review
This lesson is thoroughly sourced. It is engaging and suitable for students to understand how to measure carbon footprint from food sources. The activities in the lesson would also enable them to build their quantitative skills to determine the extent of CO2 impact on the environment. The lesson has passed our science review, and it is advised for classroom use.
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About the teacher writer
Dan Castrigano
Academic Teacher at Burlington YouthBuild
Dan Castrigano taught STEM and humanities at elementary, middle, and high schools for 11 years. From 2021-2023, he served as the Chief Content Officer at SubjectToClimate. Dan advocates for climate education and organizes for climate, social, and racial justice.
