Food on Fire: Measuring Food Energy

In this engaging nutrition lab experiment, students set food on fire. Yes, a teacher in a school actively allowed 10 and 11-year olds to ignite things (with close supervision). In this case, the combustion was used to measure the contained energy in various food items, such as pretzels, tortilla chips, celery, and walnuts, in a device called a “calorimeter.”

A basic “coffee can” calorimeter.

Before this lab, students had learned about various nutrient types, proteins, fats, carbohydrates, etc., but they did not know about the difference in stored energy within these molecules. They made predictions about which would contain the most energy, listened to some firm expectations about fire safety, and helped model how to use their data sheet. After that, students were largely independent in their groups to progress through the experiment. Roles assigned to students in each group helped to differentiate work and provide accountability to each other to stay on task.

It didn’t take long before they realized the combustive potential of fats in one tiny food item–the walnut. Burning for about 4 minutes and bringing 50 mL of water to a boiling point, students were stunned how a little snack went up in flames. Additionally, there was much frustration with celery, which despite the best efforts, just wouldn’t set on fire. A proud teacher listened on while they conjectured about why it wouldn’t burn–too much water, not hot enough, or simply not enough energy contained in it to light?

The materials for this experiment were provided by the UCSF Daly Ralston Resource Center and the Science Education Partnership. This gem in San Francisco provides teacher training, lesson plans, and educational materials for teachers. If you’re unaware of their work and also teach science, check them out!

To check out some of my materials for the unit, including graphic organizers and assessments for the lab, click the links below.

Note: Privacy for students means fewer photos in this post–sorry!