How electricity doesn't work
amasci.com
amasci.com
> After my encounter with those books, I slowly realized that my own understanding of basic electricity was flawed and incomplete. I sat down and started re-teaching myself the subject. I became aware of the source of my problem: I myself had learned a bunch of electricity misconceptions as a child. Those early misconceptions gave me a faulty foundation on which to build further knowledge. As a result, any accurate information learned later became distorted in my mind even as I learned it. If the foundation is distorted, then the "building" cannot be built. It was like trying to build a brick wall on top of a garbage pile: the incoming bricks are perfectly good, but they simply did not fit upon earlier concepts, and any structures that I managed to build kept collapsing.
Many of the textbooks he was reading through (K-6 level books) were using the pedagogical technique of http://en.wikipedia.org/wiki/Lie-to-children , where one purposefully gives inaccurate-but-simple information, planning to supplant it later with more accurate accounts once a foundational knowledge of the terms and laws of the system have been built within the student's mind. Both the misconceptions he is addressing, and his own misconceptions, show that this technique is more dangerous than it is believed to be, because people keep these inaccurate accounts, resisting learning the more complex but real accounts due to some bastardized version of Occam's razor.
Besides, your comment ignores the fact that people, in the absence of explanations (right or wrong) will make up their own model of how things work. That model is just as hard to unlearn as an incorrect view they may have been taught by an instructor. In fact, they are probably harder to unlearn because they are based on the persons own experiences.
All learning involves correcting and building on earlier concepts, there are no "tabula rasa". What is important is that people confront and integrate their own preconceptions as part of learning.
The National Academies Press book "How People Learn: Brain, Mind, Experience, and School" is a good, accessible introduction to these concepts. It's on the web at http://www.nap.edu/html/howpeople1/.
This is a relevant passage: "A logical extension of the view that new knowledge must be constructed from existing knowledge is that teachers need to pay attention to the incomplete understandings, the false beliefs, and the naive renditions of concepts that learners bring with them to a given subject. Teachers then need to build on these ideas in ways that help each student achieve a more mature understanding. If students' initial ideas and beliefs are ignored, the understandings that they develop can be very different from what the teacher intends."
Wrong, the textbook authors fully believe those misconceptions themselves. I discovered this sad fact during my K6 education consulting work back in the 80s. Lies-to-children are very different than author misconceptions: they must be carefully constructed so that they don't install permanent major misconceptions in student's minds.
For example, the idea that atoms are like tiny solar systems is a "Lie" which simply explains atomic structure in classical terms, and which turns out to be relatively harmless. It doesn't form any enormous learning barrier which entirely derails our later ability to understand orbitals and quantum chem.
Good articles on the author-misconception topic: R. Feynman's "Judging books by their covers" and S J Gould's "The case of the creeping fox terrier clone"
Reading this reminds me of the importance of mathematics for placing a hard edge on vague and potentially confusing terms like "flow" "current" "energy" "store" etc. etc.
I wonder if it is possible to give 6th graders correct intuition about electricity without math?
It's quite discouraging to see criticism from someone who didn't read what they're attacking. The article plainly states that electrons in metals are hopping all the time, even when the current is zero. Go read it. That's the whole point of that section. A bit hard to miss, unless you leapt to a wrong conclusion after only reading the title.
> because electrons "fill in" the gaps
The article specifically describes this effect. It's probably not wise to criticize things you haven't bothered to read.
That section is a simplified introduction to the concept of "electron sea" and "drift velocity." It debunks the common grade-school textbook error that electrons in metal wires only start hopping between atoms if someone connects that wire in a battery circuit (where the electrons also are supposed to remain stuck to individual metal atoms when current is zero.) This is a serious textbook misconception because it teaches kids that the electron sea doesn't exist, and it prevents them from grasping the "full pipes" fluid analogy of electric circuits as well as later concepts of metallic bond, metal reflectivity, lack of brittleness, etc.
I'm not sure it's useful to argue whether an intuitive picture of electrons hopping or not is more correct. (Electrons are in any case not really little balls that are in one place.) These are all models of the world made with specific goals, where the most "correct" model would be solving the schrodinger equation for a macroscopic system -- something that would not give you any particular insight as to how things behave.
I think the usefulness of an intuitive layman's understanding should be derived from whether it makes you conclude the correct things about the macroscopic behavior of electricity.
What bugged me about this article was that without doing a quantitative analysis of a model and comparing it's predictions to experiments - physical interpretations like whether the electrons are hopping or not are so ambiguous that they are effectively meaningless.
Kids have a pretty good mechanical model of swing sets.
That point aside, while an intuitive understanding is nice, power factor is really a mathematical construct arising from the multiplication of two out-of-phase sinusoids (i.e. voltage and current).
I think to really understand active / reactive power and pf, you need to look at the maths. It's really not that difficult. And you certainly don't need to know vector calculus, merely high school trig.
Mostly this is just arguments about semantics.
EDIT: If you want to teach electricity, describe it as a fluid acted on by fast-moving pressure waves. Resistance can be reasonably described by analogy to a viscous fluid flowing through a sponge.