CO2 Deep Dive!



30 minutes or longer
Life Science

Join databot™ in a test of the human body as you challenge yourself to hold your breath as long as possible!


Free diving is an extraordinary sport that tests the limits of the human body beyond what science thought was possible!  Record holding free divers can hold their breath as long as 11 minutes and dive deeper than 200 meters – that is over two football field lengths underwater!  How long can you hold your breath?

In PDQ2 you learned that holding your breath increases your CO2 output as your body processed more oxygen and expelled more CO2 from your bloodstream. 

In this challenge activity you will explore  this affect more deeply as you challenge yourself to hold your breath for as long as possible!  To do this, you will be challenging homeostasis – the processes in your body that work to keep things like CO2 and oxygen balanced. 

Let’s explore further with databot™!


By completing this experiment and conducting the scientific observations associated with it you will master the following knowledge! Good luck science explorer!
  • The human respiratory system is one system of many in the human body and it is responsible for breathing!
  • Carbon Dioxide (CO2) is:
    • An invisible and odorless gas.
    • Exhaled by human beings in the process of respiration.
  • Oxygen (O2) is:
    • An invisible and odorless gas.
    • One of the primary elements in the air we breathe (21%).
    • Extracted from air in the alveoli, tiny sacs in your lungs.
    • Used by the cells in your body to convert sugars to give you energy!
  • Exercise, holding your breath, and other actions affect respiration.
  • Homeostasis is your body’s systems and processes that help maintain a balance of things like oxygen and CO2 levels.
  • Scientific sensors allow us to measure the scientific world around us with better precision and accuracy.

What You'll Need

  • IOS or Android smart device with Bluetooth Low Energy (BLE) to connect to databot™
  • databot™ + Phypox App installed on your IOS or Android device
  • Plastic bag – 1 quart size


  • Recall holding your breath and the data you observed in PDQ2 when you held your breath.
  • Mentally prepare yourself to hold your breath!

Challenge (25 mins)

Your body regulates balances through something called homeostasis. For example, when you get cold you shiver and this activity warms your body. When you are too warm you perspire and this helps to cool your body.

Another example of homeostasis is balancing the correct amount of oxygen and CO2.  This is why you breathe faster when you go for a run, your body recognizes you are using more oxygen and you breathe faster to balance the new requirement.  Amazing that your body does this automatically!

When you hold your breath, your body’s processes notice that your CO2 level is increasing  and you develop an “urge” to breathe.  Free divers call this CO2 tolerance and the higher your CO2 tolerance, the longer you can hold your breath.  Free diving requires tremendous mental concentration to overcome your body’s desire to achieve balance – homeostasis. Ready to challenge your body?!  Let’s do it.

Use the following chart as a model and practice holding your breath.  When you feel the urge to breathe that is homeostasis in action!  Your body wants to keep you safe so it is alerting you that you have too much CO2 on board.  Conduct this experiment a number of times and each time, after holding your breath, exhale into your bag with databot™ and note your CO2 level. 

  • Does the CO2 level correspond in some fashion with the time of your breath hold?
  • What is the longest time you can hold your breath before your body says “no more!!”
  • Are you able to hold your breath longer after practicing?

Cool bananas – homeostasis holds no fear for you!

It’s now time for some community and group hugs. Next and final stop – a collaboration activity. Enjoy!

Next Step, Collaboration!

Educator Info

These challenge extensions are designed to be fun and “challenging” for students to take them further into the topics presented in this module.  There is no alternative for experiencing abstract data in real life!  If you have the opportunity, please share stories about your student experiences!   Use our contact form – we look forward to seeing some ingenious solutions.

Educator Info

Record holding free diving is a remarkable albeit extreme human achievement. This article provides some insight into the challenges associated with pushing the human body to this limit!

This is an amazing article as well: Free Diving : A Deep Insight Into This Incredible Way Of Life

This Healthline article provides some great insight into what happens when you hold your breath. 

Serendip Studio. Homeostasis and Negative Feedback – Concepts and Breathing Experiments

Serendip Studio. Homeostasis and Negative Feedback – Teacher Prep Notes

Breathe Cover Photo by Fabian Møller on Unsplash

Awesome underwater face mask breath-holding photo by the incomparable Sebastian Pena Lambarri on Unsplash!

Breathe by Robert O. Grover & Team databot is licensed under a Creative Commons Attribution 4.0 International License. Permissions beyond the scope of this license may be available at