Physics teacher and physics professors need to come up with a better definition of nonlinearity if we expect our students to pass any basic physics course. This is because of how education has changed over the past 10 years. I hope in this thread, we collectively as members of this forum can come up with a better definition. So I was learning about Follett's Information Skills Model from Pathways to Knowledge in education class, when I came across this sentence: http://www.intime.uni.edu/model/information/proc.html http://www.k12.hi.us/~mkunimit/pathways.htm The problem is outlines of the model itself are very linear and cyclically linear in nature at least based on comparing to examples of linearity and nonlinearity in physics. This is mainly because other than in literature, I know no other examples of nonlinearity other than in physics. This got me thinking, how do we really define nonlinearity in physics? Is really that different from how other professions definite it? However, when I took a quick glance at Wikipedia I found the worst definition for nonlinearity possible: http://en.wikipedia.org/wiki/Nonlinearity I really don't like this definition because there is a lot of physics phenomenon can be broken down into more manageable parts by the super position principle or approximately obeys the superposition principle. There is also a lot of nonlinear phenomena in physics. Furthermore, sound, light, and quantum mechanics electrons in atoms itself serve as the core of how we define to student what superposition is. We use things that can approximately obey superposition to define and introduce what superposition is!! We do it before they even learn laws of mechanics, because teachers are not required to teach superposition in 6th and 8th grade!!! Superposition and waves making up a fundamental part of the new science core standards! So, are we preparing student to fail through misunderstanding by then turning around an saying these examples of superposition are also not examples of superposition in nonlinearity? I don't think we are preparing students to fail in such a way nor do i believe that we are trying to lie to students. However, the potential for a logical reason for failure is there. Thus, I feel that using superposition as only test of nonlinearity itself, is a poor definition and way of teaching nonlinearity. So can anyone think of a better physics definition of nonlinear than how Wikipedia defines it? What do we mean by nonlinear in physics? P.S. The mathematics definition is a bit better of course; however, I am not asking about that. I only post it to show how much in contrast it is to the nonlinear definition they give for it in physics. What I am asking about is for a better definition of nonlinearity in physics not mathematics.