We make a nice version of this classical demo which works well as an interactive exhibit. We wrestled with the same problem until someone in the workshop had a brainwave and tried flimsy plastic bags. They are much thinner than ordinary polyethylene bags. They work wonderfully well, require far less negative pressure to operate, and look surprisingly realistic.

Perhaps in 'American' you call them 'diaper bags'? In English they are 'nappy bags'. Once, we even found some pink ones. 

Ian Russell
www.interactives.co.uk

------Original Message------
From: Daniels, Alissa
Sender: Informal Science Education Network
To: [log in to unmask]
ReplyTo: Informal Science Education Network
Subject: harder to breathe
Sent: 4 Nov 2009 20:37

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we've got one of those simple little models of the lungs where you move a lever that changes the pressure inside the chamber and the lungs inflate. We've been using regular balloons for this, which worked all right but not great because they don't inflate at the same rate. Where does one get good "lungs"?

thanks all!
AD

~~~~~~~~~~~~~~~
Alissa Daniels, Science Program Manager/Senior Educator
Boston Children's Museum
617 426 6500 .342
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" (I found it!) but "That's funny..."  " --Isaac Asimov
~~~~~~~~~~~~~~~

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