Subject: Systems Language - closed loops

Posted by Tim Joy on 2/6/2010
In Reply To:Systems Language - closed loops Posted by Niall Palfreyman on 2/5/2010

Message:

From Niall's recent post on the closed loop:

> However when I look at exploding rabbit populations in our first approach to exponential growth, I want the students to come to grips with a rather more abstract situation: births influences the rabbit population, which dictates the birth rate. Here it is no longer a question of two separate agents influencing each other, but rather a process influences a stock, which in return dictates (not influences) the process. There is something about this SD way of viewing the loop which my students find difficult to absorb, and it seems to them a needless abstraction.
>
> This is the situation I'd like to find new vocabulary for.
>

A teaser question that Barry Richmond often asked a new audience . . . how is it that birth rates have been falling virtually everywhere around the globe for the last 20 - 30 years, and yet the population continues to climb and will climb for another 30 to 40 years?

Most people are flummoxed by this question. Unless, there are folks in the audience who have in their heads what Niall describes (they'd also have to know about a death outflow), this is a very hard concept. It is not intuitive.

What might help us move students from seeing this as "needless abstraction" to a clearer picture of an illusory concept?

Tim

Follow Ups:

Systems Language - closed loops - Niall Palfreyman 2/7/2010 
Systems Language - closed loops - Warren Farr 2/7/2010
Systems Language - closed loops - Richard Turnock 2/7/2010
Systems Language - closed loops - Kathy Arizmendi 2/6/2010