Monday, January 23, 2012

Model Lungs

I had too much fun that I couldn't share.  I was recently invited to speak to a group of Girl Scouts that meet once a month to have activities and discussions based around "technology."  The girls were well within the range of ages I've worked with before, but not of the blog target audience.***   However, I thought it would be useful for anyone who might be looking for a biomedical activity for late elementary-early middle school since there isn't too much info out there.

Background: I met the leader through work and told her about this blog and my mission (this blog is fun to write and share!).  I also told her that I've done an activity based off of this lung modeling activity with high schoolers, but I thought it would be easy enough for the age group.  She agreed.

The group of girls ranged from 8-12 years old.  I told them about wanting to be an engineer since playing with Lego Robots at age 8 and a little bit of my background - where I came from and went to school and that I'm a dancing mechanical engineer doing gait analysis.  I also told them about two modeling experiences I had.  No, not runway modeling.  I created a finite element (computer) model of a knee with a total knee replacement and made the knee walk.  I explained that the company could then exchange out different knee replacement designs and see how it would affect someone's walking.  I then told them about "bench modeling" and how I created a super simple, but effective, model through research.  I got to build the model and test it out for a super cool medical device company (and - I got to go to the slaughter house to pick up cow parts, even better!).  We talked about the importance of conducting modeling - main reason is safety, and the governing regulatory body - the Food and Drug Administration (FDA) that makes rules to keep people from being harmed.

I then talked about lungs.  We all have them.  Some of us even have a common problem, asthma.  We discussed basic anatomy of the lungs and a little bit about how asthma affects the lungs.  I introduced the materials they'd have to work with and gave them this handout that I made two years ago when I did it with the high schoolers.

Here's the basics (but check out the handout for a nice layout and some pictures)

2 liter soda bottle with the bottom cut off
2 bendy drinking straws
3 small rubber bands
1 large rubber band
1 small produce bag

Cut off the bottom of a 2 liter bottom.  Attach balloons to the bendy part of the straws using a small rubber band, but be cautious not to make it too tight, as the airways would be closed and the model wouldn't work.  Tie the straws together with another small rubber band, again making sure that the straws weren't pinched closed.  Place the straws in the neck of the bottle and close off with modeling clay.  Take the produce bag (you might need to trim it down a little bit) and place it over the bottom of the bottle, attach with a larger/thicker rubber band.  Make your model breathe by pushing in and out on the produce bag (aka the diaphragm), making sure the bottle is air tight.  The "lungs" will fill with air, but don't expect them to be blown up like party balloons.  It might take a little adjusting of the bag and pulling on the bag to fill the lungs the first time, but then it should work well.  If it doesn't work, begin troubleshooting.  The airways are most likely clogged somewhere along the lines.  Note that I do not use binder clips, as I felt it was an unnecessary expense.  Using your fingers to pull the produce bag in and out for breathing works just fine.


Once the model is working, talk about what they can do to model asthma and other problems in the lungs.


All of them were able to get a working model, and most of them could model asthma (swollen airways).  The easiest way to model asthma was to squish the straw with a rubber band/the clay.  My favorites are those who use clay to clog up the straws .  Some of them were challenged to model what happens during pregnancy and why some ladies get short of breath easily (having to do with the baby in the way of the diaphragm).

The girls were very on top of their game that we ended the model making early.  I was asked to do an impromptu discussion at the end (instead of letting the girls roam free which would ultimately end in indoor soccer).  We talked about other lung problems, like cystic fibrosis, and how some people get double lung transplants.  We discussed what's going on during CPR.  We talked about smoking and tracheotomies (and that gross anti-smoking commercial of the smoker talking through the hole in her neck - Stages 2010).  The double lung transplant discussion led to a few other medical type questions and discussions (body rejection, relying on and being kept alive by machines waiting for donors).  The leaders even discussed organ donation, sweet!  Preaching it young.  So there's an array of great material to introduce to young kids just by making soda bottle lungs!

I felt good about volunteering.  I hope it inspired them to at least learn more about biomedical/mechanical engineering and/or the medical field.  The girls might even come to the gait lab next year to see what goes on there.  I can't wait.

***Note that my J tried to play with my model lung I created for the demo multiple times.  Once, he even brought it out to show his friends.  He totally was able to make it breathe, though I'm sure he couldn't explain what was going.  It was a neat toy with balloons and straws.


  1. We loved having you at our Girl Scout Tech Time and I know the girls really enjoyed it. You were great with the kids. I hope we get to visit the Gait Lab another time. Carol Gilbert

  2. Will playdough work instead of clay?

    1. Playdough should work too (it'll probably dry out sooner, like after a day or two - so if it's a one day project go for it. If you want to make it last longer, say for a science fair display, I'd recommend going with the clay). Just whatever you use, make sure it covers the hole in the bottle (not the straws).

  3. How would you model that of someone who is a smoker or lives in a polluted area?

    1. Great question, Vicky! Maybe you can use an older balloon that may not be as stretchy or add some residue/weight to the balloon.

  4. I know this is a late response for Vicky, but anyone else reading could this:
    Pulmonary Fibrosis can be replicated by doubling the balloon on one lung making it more difficult to inflate. By only doubling the one lung you will see the difference between the single balloon (healthy lung) & the double balloon lung (diseased lung).