← How Scientists Count Farts

Teacher guide

Middle school, high school and college

Raven joined a University of Maryland study that counts farts with a sensor clipped to her underwear. Students watch her video and work out why the old count of 10 to 14 farts a day came out so low.

Start the lessonPrint the worksheet
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At a glance

Middle school
Grades 6 to 8 · About 23 minutes
High school
Grades 9 to 12 · About 38 minutes
College
College · About 35 minutes
Materials
The worksheet for your level and a screen for the video.
Grouping
Students work alone. For partners, pair students for Questions.
Phenomenon
For decades, doctors said healthy adults pass gas about 10 to 14 times a day. Those counts came from people keeping track of their own gas. A sensor clipped to underwear counted an average of 32 times a day.
Topics
Farts and other intestinal gas, digestion, gut bacteria, a sensor worn on underwear, joining a research study, self-report versus measurement.

Preview the video before sharing it with your class.

Video and transcripts

  1. 1

    I’m farting for science!

    Dr. Raven joins the Human Flatus Atlas, a University of Maryland study, and wears a hydrogen sensor on her underwear for three days. The video runs 87 seconds.

    Watch on YouTube
    Transcript

    Transcribed from the posted video on YouTube.

    Guys, I signed up for a clinical trial to fart. To fart. To fart.

    I want to sign up to be in as many clinical trials as I can be in because I want to help science move forward. And so as I was looking on ClinicalTrials.gov, I found one of the few that I was actually qualified for. And all you have to do is wear this device and fart.

    The Human Flatus Atlas is a scientific research project led by Dr. Brantley Hall at the University of Maryland. They’re trying to get the record straight. Old data suggests that people only fart like 10 to 14 times a day. But the data that they’re collecting in these smart underwear biosensors shows that people might be farting like three times more than that.

    So here’s the biosensor. It can read hydrogen gas. And hydrogen gas is produced by the bacteria inside of your gut that help to break down the food that you eat. Bacteria in your gut make your fart.

    I’ve been wearing this biosensor on my underwear for the past few days. They require three days of data collection. They have an app. All you have to do is take a picture of the food and drink that you have, submit it. And then this biosensor on your underwear is collecting the data of how much hydrogen gas that you’re putting out.

    Once you start collecting data, this thing starts spitting out information. It’s crazy because this thing says that at one point, my flatus count was 25 per hour. And I like, what counts as a fart? Like you, I just...

    Have you ever participated in a clinical trial or research study? What was it like? And let me know if you see any interesting research studies or trials on the ClinicalTrials.gov website, ’cause I might want to do it too, girl. I’m trying to help. I’m Dr. Raven Baxter. Follow me for more science. Do, do, do, do, do.

Your word of the day is

FLAY-tus

fla-to blowfrom Latin flāre
-tusthe act offrom Latin -tus

Flatus. Gas made in the intestines and passed out of the body. Flatus is the science word for the gas in a fart.

Word partComes fromMeaning
fla-Latin flāreto blow
-tusLatin -tus, an ending that names the action of a verbthe act of
microbiome (bonus word)Greek mīkrós, “small,” and bíos, “life,” with the noun ending -ome, as in biomeall the microbes living in or on a body or in a place

Same roots, other subjects

  • History and civicsInflation, a steady rise in the general level of prices, comes from Latin inflāre, “to blow on or into, puff out.”
  • BiologyFlatulent describes food that makes gas in the gut. The word comes from New Latin flātulentus, formed from flātus.
  • Physical scienceTo inflate a balloon or a tire is to fill it with air or another gas. Inflate joins in- and flā-, “blow.”
  • EnglishTo conflate two things is to fuse them into one. Conflate comes from Latin conflāre, “to fuse together,” from con- and flāre, “to blow.”
  • MusicIn Italian, fiato means breath and also a wind instrument. The word comes straight from Latin flātus.
  • World languagesSpanish inflar, “to inflate,” comes from Latin īnflāre, with the same flā- root.

Word hunt. Ask students to find three more words with the fla root, “to blow,” and say what gets blown or puffed up in each one.

Flatus is the scientific word for the gas the Smart Underwear measures. Raven says the word twice in the video, in “Human Flatus Atlas” and “flatus count.” Microbiome, the bonus word, names the community of microbes, such as gut bacteria, that live in or on a body. American molecular biologist Joshua Lederberg coined microbiome in 2001 from microbe and biome. The worksheets carry a short version. Use these for discussion or a word hunt.

Lesson flow

Lesson flow level
  1. 3 minPredictStudents answer the question and write one sentence.
  2. About 2 minVideo
  3. 4 minWord of the dayBreak the word into its parts together.
  4. 8 minQuestionsStudents answer on their own, then share out. With partners, pairs discuss first.
  5. 5 minExit ticket
  1. 3 minPredictStudents answer the question and write one sentence.
  2. About 2 minVideo
  3. 4 minWord of the dayBreak the word into its parts together.
  4. 8 minQuestionsStudents answer on their own, then share out. With partners, pairs discuss first.
  5. About 15 minClaim, evidence, reasoning and Going further
  6. 5 minExit ticket
  1. About 2 minVideoPlay the video once.
  2. 4 minWord of the dayBreak the word into its parts together.
  3. 3 minPredict
  4. About 20 minRead the paperThe paper reading works as homework or a discussion section.
  5. 5 minExit ticket

Video simplifications

“I signed up for a clinical trial to fart”
ClinicalTrials.gov lists the Human Flatus Atlas (NCT07134543) as an observational study. Participants wear the device and log their meals, and the study tests no treatment. “Research study,” the phrase in the video’s caption, fits better than “clinical trial.” The registry listing matches where Raven says she found the study.
“Old data suggests that people only fart like 10 to 14 times a day”
Supported. Furne and Levitt counted 10 a day in 1996, Levitt’s 1979 paper listed 14 plus or minus 6 as normal, and the Human Flatus Atlas site cites 10 to 14.
“People might be farting like three times more than that”
The Smart Underwear average of 32 is about three times 10 and a little more than twice 14. The University of Maryland release says “roughly double.”
The caption says the old number “came from asking people to remember”
The older counts came from small studies and from people recording their own farts in diaries, a kind of self-report. Recording farts as they happen still misses sleep and unnoticed farts, and the Maryland team lists imperfect memory among the problems.
“Hydrogen gas is produced by the bacteria inside of your gut”
Hall’s team says the hydrogen in flatus is produced only by gut microbes, a broader word than bacteria. Other gut microbes, including methane-making archaea, use up hydrogen.
“My flatus count was 25 per hour”
Raven’s 25 is a peak hourly rate from her own device. The study’s 32 is a daily average, and the two numbers cover different spans of time.
“They require three days of data collection”
Supported. The ClinicalTrials.gov listing asks participants to wear the device at least 12 hours a day for three days in a row and to log meals with photos in an app.
Pronunciation
Flatus is FLAY-tus. Microbiome is MY-kroh-BY-ohm.

Worksheet

Worksheet level
Print the middle school worksheet
How Scientists Count FartsMiddle school learnscience.org

Predict

A fart is gas that leaves your body through your bottom. For many years, doctors said healthy people fart about 10 to 14 times a day. Do you think healthy people fart more than 14 times a day?

Circle one. Yes / No

Watch

  1. I’m farting for science!youtube.com/shorts/8OqwMEsxD38

Word of the day

Flatus (FLAY-tus). The science word for the gas in a fart.

Word partComes fromMeaning
fla-Latin flāreto blow
-tusLatin -tusthe act of
  • Inflate means to fill with air, like blowing up a balloon. Inflate comes from the same Latin root, flāre, “to blow.”
  • In Italian, fiato means breath. The word comes straight from Latin flātus.

Bonus word. Microbiome (MY-kroh-BY-ohm). All the tiny living things, like bacteria, that live in or on a body or in a place. Micro- means small, and bio- means life.

Questions

  1. For many years, doctors said healthy people fart about 10 to 14 times a day. Those numbers came from people keeping track of their own farts. A sensor is a tool that detects something. A sensor clipped to underwear counted an average of 32 farts a day. Why would people counting their own farts come up with fewer than the sensor?

    Hint. Think about the hours you spend asleep. Can you count anything while you sleep?

  2. The Smart Underwear sensor Raven wore in the video detects hydrogen, a gas found in farts. Where does the hydrogen gas in a fart come from?

    Circle one. Air you swallow / Bacteria in your gut / Your lungs

    Hint. Listen to what Raven says the bacteria in your gut do with your food.

  3. In the Smart Underwear study, the lowest count for one day was 4 farts. The highest count for one day was 59 farts. Why do scientists count farts in lots of people before they say what’s normal?

    Hint. Could one person’s count tell you what’s normal for other people?

  4. In the video, Raven asks, “What counts as a fart?” Scientists decide what counts before they start counting. Why do scientists need to agree on what counts as one fart before they compare their numbers?

    Hint. Imagine one scientist counts tiny farts and another scientist skips tiny farts. Could the two scientists’ numbers match?

Exit ticket

Scientists can ask people to keep track of their own farts, or scientists can measure farts with a sensor. Which gives scientists a better fart count, keeping track yourself or measuring with a sensor? Why?

Hint. Think about what people miss while they sleep, and how easy it is to lose count of something you do without noticing.

Print the high school worksheet
How Scientists Count FartsHigh school learnscience.org

Predict

A fart is gas that leaves your body through your bottom. For many years, doctors said healthy people fart about 10 to 14 times a day. Do you think healthy people fart more than 14 times a day?

Circle one. Yes / No

Watch

  1. I’m farting for science!youtube.com/shorts/8OqwMEsxD38

Word of the day

Flatus (FLAY-tus). Gas made in the digestive tract and passed out through the anus.

Word partComes fromMeaning
fla-Latin flāreto blow
-tusLatin -tusthe act of
  • Inflation, a steady rise in prices, comes from Latin inflāre, “to blow on or into, puff out,” with the same flā- root.
  • To conflate two things is to fuse them into one. Conflate comes from Latin conflāre, from con- and flāre, “to blow.”

Bonus word. Microbiome (MY-kroh-BY-ohm) is the community of microorganisms, together with their genetic material, living in or on a body or in an environment. The word joins Greek mīkrós, “small,” and bíos, “life,” with the ending -ome, as in biome.

Questions

  1. A 1979 paper by gastroenterologist Michael Levitt listed the normal number of farts as 14, plus or minus 6, a day. In a 1996 study, 25 healthy people kept count for a week and averaged 10 a day. The Smart Underwear study, which used a hydrogen sensor, found an average of 32 a day, with daily totals from 4 to 59. Why could counts people keep for themselves come out lower than a sensor’s count? Give two reasons.

    Hint. Think about sleep, and about farts too small or quiet to notice.

  2. In a 1991 study, 10 healthy volunteers wore a flexible tube, placed in the rectum, that collected their gas for 24 hours. When 6 of the volunteers drank a liquid diet with no fiber for 48 hours, the hydrogen in their gas nearly disappeared. What does the drop in hydrogen tell you about where the hydrogen in flatus comes from?

    Hint. The small intestine can’t digest some fiber. Which living things in the large intestine could use fiber that reaches them?

  3. In the same 1991 study, the volunteers also wrote down each time they noticed passing gas, a median of 8 times. The number of times a volunteer noticed passing gas did not line up with how much gas the tube collected. What does the 1991 study suggest about using people’s own notes to measure gas?

    Hint. When notes and a measurement disagree, which one would you trust to measure gas?

  4. The Smart Underwear detects farts by the hydrogen gas in them. In the video, Raven asks, “What counts as a fart?” Picture a careful counter wearing a sensor that works correctly. How could the person’s count and the Smart Underwear’s count still disagree?

    Hint. Some farts carry little hydrogen, and some farts are too small to feel.

Claim, evidence, reasoning

Older studies, many based on counts people kept themselves, found about 10 to 14 farts a day. The Smart Underwear study found an average of 32. Which number is closer to how often healthy adults fart? Make a claim, back it up with evidence, and explain your reasoning.

Hint. Compare how each number was collected.

Going further: Zen Digesters

  1. The Smart Underwear team is recruiting people it calls Zen Digesters. Zen Digesters eat 25 to 38 grams of fiber a day yet pass little gas. Gut bacteria break down fiber without oxygen. This breakdown, called fermentation, releases gases such as hydrogen. Some gut microbes use up hydrogen and turn the hydrogen into other products, such as methane. How could a Zen Digester eat plenty of fiber and still make so little gas? What measurement would test your explanation?

    Hint. Think about which microbes live in a Zen Digester’s gut. The team plans to collect stool samples from Zen Digesters.

Exit ticket

Older studies, many based on counts people kept themselves, put the normal number at about 10 to 14 farts a day. A hydrogen sensor now puts the average at 32. A number in science can change when scientists find a better way to measure. How does the Smart Underwear study show that?

Hint. Name what changed between the older studies and the sensor study.

Print the college worksheet
How Scientists Count FartsCollege learnscience.org

Watch

  1. I’m farting for science!youtube.com/shorts/8OqwMEsxD38

Word of the day

Flatus (FLAY-tus). Gas produced in the intestines, partly by bacterial fermentation of undigested food, and passed through the anus.

Word partComes fromMeaning
fla-Latin flāreto blow
-tusLatin -tusthe act of
  • Flatulent comes from New Latin flātulentus, formed from flātus.
  • Italian fiato, “breath,” comes from Latin flātus, and Italian also uses the word for a wind instrument.

Bonus word. Microbiome (from micro-, “small,” bio-, “life,” and -ome, as in biome) names the microorganisms in or on a body or in an environment, together with their genetic material. American molecular biologist Joshua Lederberg coined the word in 2001.

Predict

  1. Australian researchers asked 6,416 people to log each fart in a phone app, as close as possible to the moment it happened, on at least 3 days. Make a guess before you read the paper. How many farts a day do you think the average participant logged? Give your reason in one sentence.

    Hint. In the video, Raven gives an old estimate of 10 to 14 a day and a sensor estimate about three times higher. Would counts that people tap into an app come out closer to the old estimate or to the sensor estimate?

Read the paper

Brindal and Baird, “Regular Flatulence Patterns Among Community-Dwelling Individuals in Australia,” JAMA Network Open, 2026. The paper is free to read.

Emily Brindal and Danielle Baird of Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) created a phone app called Chart Your Fart. From November 2024 to February 2025, 6,416 participants aged 14 and older logged 360,192 farts, each as close as possible to the moment it happened, for a mean of 10 days. The table below comes from the paper’s Table. It compares who joined with Australia’s population aged 14 and older, and it gives the farts logged per day. It leaves out the 146 participants in the paper’s Other gender group, which has no population figure.

GroupShare of sample, %Share of Australian population, %Sample minus population, percentage pointsFarts logged per day, mean (SD)Farts logged per day, median (IQR)
All participants1001005.0 (3.8)3.8 (2.5 to 6.2)
Female50.750.74.8 (3.6)3.8 (2.4 to 6.0)
Male47.049.35.2 (3.9)4.0 (2.5 to 6.5)
Age 14 to 2513.317.74.4 (3.4)3.3 (2.2 to 5.3)
Age 26 to 4538.133.95.2 (3.8)4.0 (2.6 to 6.5)
Age 46 to 6538.729.25.0 (3.9)4.0 (2.5 to 6.3)
Age 66 and older10.019.24.8 (3.7)3.7 (2.4 to 5.8)

  1. Quantitative reasoning Fill in the blank column of the table. Which age group did the Chart Your Fart study oversample the most? Which did it undersample the most? Would weighting the age groups to match Australia’s population move the mean of 5.0 farts a day by much?

    Hint. A positive difference means a group made up more of the sample than of the population. Compare each age group’s mean with 5.0.

  2. Process of science The Chart Your Fart app couldn’t tell a day with no farts apart from a day the participant forgot to log, and participants had no way to report a day with zero farts. If some participants had days with zero farts, how would leaving those days out change the Chart Your Fart study’s mean?

    Circle one. Make the mean too high / Make the mean too low / No change

    Hint. An average of only the days with farts leaves out the zeros.

  3. Pathways and transformations of energy and matter The paper’s Figure shows logging rose through the day and peaked between 6 and 10 pm, a pattern that overlaps with when Australians eat the most food energy and fiber. What mechanism could link the evening peak in logged farts to food eaten earlier in the day? What besides gut chemistry could produce the same pattern?

    Hint. Fiber passes the small intestine undigested. Then think about when people are free to log.

  4. Process of science The app participants logged a mean of 5.0 farts a day. The Smart Underwear study, which used a hydrogen sensor, found a mean of 32. How many times larger is 32 than 5.0? How would you design a study to measure how many farts a self-report app misses?

    Hint. Have the same people use both methods at the same time.

Exit ticket

Brindal and Baird’s table summarizes 360,192 farts logged by 6,416 people. What does the Brindal and Baird table show about how often people log farts? What’s one question the table can’t answer?

Hint. Start with the mean and the median. Then think about the farts a person can’t log.

Standards

The lesson builds toward four Next Generation Science Standards (NGSS), the most widely used US science standards. Some states, like Texas and Virginia, write their own. NGSS covers kindergarten through grade 12. The college worksheet uses the AAAS Vision and Change framework for undergraduate biology. HS-LS2-3 also connects to the nature of science idea “Scientific Knowledge is Open to Revision in Light of New Evidence,” the theme of the high school exit ticket.

LevelStandardLesson partPracticeCrosscutting concept
Middle schoolMS-LS1-7. Model how food is broken down and rearranged into new molecules as it moves through an organism (core idea LS1.C)Middle and high school worksheets, Questions 2Developing and Using ModelsEnergy and Matter
Middle schoolMS-ETS1-3. Analyze data from tests to find similarities and differences among several solutions (core ideas ETS1.B, ETS1.C)Middle and high school worksheets, Questions 1 and exit ticket, comparing two ways to countAnalyzing and Interpreting DataNone listed for MS-ETS1-3
High schoolHS-LS2-3. Construct and revise an explanation for the cycling of matter and flow of energy in aerobic and anaerobic conditions (core idea LS2.B)High school worksheet, Going further and exit ticketConstructing Explanations and Designing SolutionsEnergy and Matter
High schoolHS-ETS1-3. Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs (core idea ETS1.B)High school worksheet, claim, evidence, reasoningConstructing Explanations and Designing SolutionsInfluence of Science, Engineering, and Technology on Society and the Natural World
CollegePathways and transformations of energy and matter. AAAS Vision and Change core conceptCollege worksheet. Questions 1 and 4 cover quantitative reasoning, questions 2 and 4 process of science, and question 3 pathways and transformations of energy and matter.Core competencies: process of science; quantitative reasoningCore concept: pathways and transformations of energy and matter

Sources

Brindal and Baird call their study, “to our knowledge,” the first to describe real-time flatulence habits in a large, general population. The hedge shows students how carefully scientists word a first.

Conflicts of interest. Hall and Botasini have filed patent applications for the Smart Underwear and founded Ventoscity, the company that licensed the device. Brindal and Baird reported none. College classes can discuss how disclosures help readers weigh a study.

The Human Flatus Atlas enrolls adults 18 and older. The lesson does not ask students to join.

This video draws on several research teams. The lesson credits each team.

TopicWho found itWhere it was published
Smart Underwear, an average of 32 farts a day, daily totals of 4 to 59Santiago Botasini, Brantley Hall and colleagues, University of MarylandBiosensors and Bioelectronics: X, 2025
Human Flatus Atlas design, three days of wear, up to 500 adultsBrantley Hall’s lab, University of MarylandClinicalTrials.gov, NCT07134543
A normal of 14 plus or minus 6 farts a dayMichael LevittDigestive Diseases and Sciences, 1979
10 farts a day over one weekJ. K. Furne and Michael LevittDigestive Diseases and Sciences, 1996
Gas collected by tube, fiber and hydrogen, noticed episodes versus collected gasJ. Tomlin, C. Lowis and N. W. Read, Royal Hallamshire Hospital, Sheffield, UKGut, 1991
6,416 people logging farts in an appEmily Brindal and Danielle Baird, CSIRO, AustraliaJAMA Network Open, 2026
Gut gas from fermentation without oxygen, bacteria that make no gasI. Rowland, G. Gibson, A. Heinken, K. Scott, J. Swann, I. Thiele and K. TuohyEuropean Journal of Nutrition, 2018
Gut microbes that use up hydrogenN. W. Smith, P. R. Shorten, E. H. Altermann, N. C. Roy and W. C. McNabbGut Microbes, 2019

The Levitt 1979 and Furne 1996 papers sit behind a paywall. The rest are free to read. The Botasini paper is open access. Its numbers in this lesson come from the University of Maryland release and the paper’s abstract.

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