1. Even a simple system is complicated!!
Any system can be examined by looking at what it does (function), and the parts (structures) and interactions (mechanisms or behaviors) that achieve the given function

2. Describing (complex) systems
Structure-behavior-function language provides a way to break a complicated system down to easily handled chunks
Basically, What, How, Why
In plain English” Something does something (to something) to accomplish something else”
Normally hierarchical-functions accomplished with sub-functions (It’s turtles all the way down!)
What= structure; How=behavior or mechanism; why = function
Any system that achieves a function can be described by smaller systems that accomplish sub-functions. The function of a car is to drive, but subsystems (engine, steering, etc) each perform sub-functions that together make a car. That is, systems have a hierarchy.

3. Direct light straight out
Curved surface bounces light so that it leaves at same angle it came in
Redirect incoming light
Mirrored surface reflects light to strike
other side of eye at the right angle
The function here is “reflection” –The eye directs light (note this is keyed wrt to the structure function designations on the previous slide. The eye (system) can be broken down into sub-systems (and subfunctions) given on the right.
Note that “bounce” and “reflect” have very specific meanings…
Note: going down explains “how, going up is “why” (that is what is the relation of the sub-function to the others)
Direct incoming light to mirror
The eye directs light out so that it exits at the same angle it went in
Curved surface bounces direct light to focus it on mirrored back reflector