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Design Challenges

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Design Challenges

Solving Problems with Ingenuity and Grit!

Prepare yourself for some challenging times in this exciting engineering series.

Overview - The Cave of Dogs






The Cave of Dogs poses a real-world challenge related to the denisty of gases, specifically CO2 that settles into a thick layer in a real cave located in Italy.  CO2 is a deadly gas in that it displaces oxygen if there is too much of it, so this challenge is to mitigate and control CO2 levels!

The Scenario

Imagine a mysterious cave  that affects people and animals quite differently as they enter to explore. Such a place actually exists, it is called the Cave of Dogs and it is located near Naples, Italy. The “mystery” of the cave is how it affects different animals.  A human can enter and walk about with no problem, but dogs or other small animals that enter pass out. Yikes!

The answer to the mystery?  If you haven’t already guessed, the more dense CO2 gas settles into the lower areas of the cave and animals that are close to the ground asphyxiate – there is no oxygen! Humans, walking upright, are above the CO2 level and able to breathe in the life-giving oxygen that CO2 displaces at a lower level. This mysterious cave has a fumarole from which volcanic gases including CO2 seep into the cave making it a very dangerous place to be if you want to be able to breathe!

Volcanic fumaroles, such as those found in the Cave of Dogs in Italy, are volcanic vents that release gases such as CO2.

Note how the CO2 concentrations vary at different levels in the Cave of Dogs.   Why are CO2 levels higher at the lower levels?

Note the effects of CO2 levels. Is the concentration below 1 meter in height in the cave a dangerous level?

The Challenge


The Cave of Dogs Design Challenge is two-fold, and can be applied as a whole, or individually in parts.  This challenge provides an excellent introduction to the concepts of how gases have different densities and how gas buildup, such as CO2, can be highly hazardous.  

Part 1: The Cave

In this challenge you will create your own simulated version of the Cave of Dogs that has a regular inflow of CO2 into the cave. Use databot™ to monitor the CO2 levels.    Think of various solutions to creating a simulated cave in which you can feed a steady stream of CO2.  How will you produce CO2 and how will you feed it into this environment?

Part 2: HVAC to the Rescue!

Heating, Ventilation, and Air Conditioning is a critically important field of study in which engineers design air flow systems for our living spaces.  For example, poor engineering design can result in high levels of Carbon Dioxide in your living or workspace if there is inadequate ventilation.  Use databot™ to take CO2 readings in your classroom or home – are the levels within an acceptable range?  Are they higher than 1,000 PPM in any areas?

You Design Challenge is to brainstorm, design, and produce a working ventilation system that will keep your Cave of Dogs model, created in the first half of this challenge, at a CO2 level of 400 PPM (the lowest level databot™ can read).

Remember Your Engineering Design Process!


NASA has been kind enough to provide a detailed approach to the Engineering Design Process for creating solutions to the many problems our planet faces.   Here are the steps in detail for reference.  Go forth and design well!

  • Ask.   Ask questions to narrow the scope of the challenge at hand. Make sure you clearly understand the problem in full.
  • Imagine.  Brainstorm and imagine possible solutions to the challenge. This might involve researching existing solutions or previous attempts to solve similar problems.
  • Plan. From your list of brainstormed ideas,  narrow down the options and sketch or model the approach. Select what you consider to be the single best option that has the highest likelihood of success. This idea will be the single solution to prototype!
  • Create. Build a working prototype based on your design parameters.
  • Experiment. Time for testing! Experiment with your prototype and gather data to determine its strengths and weaknesses.
  • Improve. After gathering the data for analysis and identifying areas of improvement,  implement improvements to your design.

Follow the process and succeed!  Good luck engineers!

Explore More Design Challenges in the Left Hand Menu!

Educator Info

How We Breathe, Molly Kampf. 2018.

UC Colorado Boulder, Teach Engineering. Lesson: Breathe In, Breathe Out

UC Colorado Boulder, Teach Engineering. Hands-on Activity: Create Model Working Lungs: Just Breathe.

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

Serendip Studio. Homeostasis and Negative Feedback – Teacher Prep Notes

Khan Academy Video: The carbon cycle

Khan Academy Video: Meet the lungs

Khan Academy Video: Oxygen movement from alveoli to capillaries

Khan Academy Video: Inhaling and Exhaling

Design Challenge Gear Image from the incomparable Image by MustangJoe on Pixabay!

Engineering Design Process and image courtesy of NASA, public domain.

© Copyright. aRbotics LLC. 2020. All rights reserved.

Permissions for usage and distribution beyond the scope of databot™ customers using these materials can be requested at

NASA Engineering Design Process Resources can be found at their BEST website. 

Stanford’s K12 Lab has some remarkable resources for Design Challenges as well as comprehensive PD programs.  Check them out!

databot™ Cave of Dogs curriculum module has additional background information on the cave as well as examples of how to create a simulated cave.