In this exercise, students use a controlled environment to demonstrate the build up of gases in the large intestine. Through their observations, they will better understand the mechanisms that create flatulence (passing gas) and how microorganisms can be beneficial to overall health.

What Makes Flatulence (PDF)


Intended Audience








Learning Objectives

After completing this activity, the student will be able to:

  1. Investigate the factors that lead to the release of gas from our large intestines.
  2. Recreate these factors within a scientific setting.
  3. Hypothesize how gas is made in the large intestine based on observations of their experiments.
  4. Articulate why this process is important for digestion and overall health.


Student Background

Students may not have heard of the word “flatulence” before, but they most likely have had some experience with it. Flatulence is the word scientists use to refer to the gas that builds up in your lower intestines and is expelled through the anus. You may want to give students a chance to be silly to get over their initial embarrassment about the content. It may even help to have them share the words they use at home for “passing gas” and remind them that for the remainder of the class everyone will be expected to utilize the words that scientists use. The build up of gas comes from two main sources 1) air swallowed while eating and/or drinking and 2) by the breakdown of carbohydrates in the intestines. This lesson will deal with the second source of gas that leads to flatulence.



Digestion, intestines, bacteria, chyme, flatulence, carbohydrates


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