The problem is the kid has no way to picture "charge" and "potential" and so those words, to him, are words without corresponding pictures -- in other words, just words. We need a picture, a model, that is accurate enough so it can be used (a) to explain the behavior of the system, and (b) to make predictions about how changes in the system will affect that behavior -- but at a level of abstraction that can be easily grasped by a ten-year-old. Opening and closing gates, water flowing through a pipe, line-dancing-electrons moving left and right, rubbery sheets stretching and springing back -- these are the kind of things the kid has first-hand, tangible experience with. "Charge" and "potential" and (from another post) "voltage superimposed on a bias voltage" are things he has no experience with and thus cannot picture in any meaningful way.

The problem with that is you are building the wrong mental picture of matter being the carrier of ENERGY and it's very hard to unlearn an incorrect first impression. It's usually best IMHO just to say 'this is the way it is' until they gain a good foundation of facts. Children will remember if it's repeated with questions, quizzes and FUN activities. Charge and potential leads directly into fields and when you understand fields you understand 'Electricity'. You can't explain by analogy unless they really understand the other principle at some level and most people don't understand closed loop hydraulic circuits or elementary physics. Teaching children about charge, potential and fields is easier if they understand the basics of gravity, kinetic and potential energy. (I've taught my 10yo the correct physics at her level) Example: Gravity is a force that's invisible but it's easy to demonstrate correctly using common objects to build the correct mental picture. So a good demonstration of electrical energy is to use gravitational energy.

I made a school gravity/electric demo project for my little girl with only three things.

A strong magnet with a hole, a plastic pipe that closely fits the magnet and matching diameter but shorter copper pipe.

You simply first hold the plastic pipe vertical and drop the magnet down it while measuring the time and how loud it hits the bottom. Then you take the shorter copper pipe (that's not magnetic) and drop the magnet down it while noting the same information.

If you explain how picking up the magnet from the bottom of the pipes to the tops gives it potential energy that when released causes it to fall down the plastic pipe quickly as kinetic energy with a loud boom but with the copper pipe it moves down slowly with a gentle tap on the bottom as energy is converted from gravity to electricity from the moving magnetic field that creates an electric field (voltage) causing charge to flow (current) in the copper pipe that in turn creates a magnetic field that slows the magnets fall with the energy of electricity. Then you can explain insulators, conductors and resistance in terms of energy lost when charges move in conductors as electrons. You can do all of this in a physics correct way that's also fun and builds the correct mental foundation to see how the tube amp works.

 

I can imagine the first question. "If we don't need matter to be the carrier of energy, why do we need to build an amplifier at all? Why don't we just have the energy jump into the speaker?"

 

I can imagine the first question. "If we don't need matter to be the carrier of energy, why do we need to build an amplifier at all? Why don't we just have the energy jump into the speaker?"

That is a question that means they are learning so it's a good one because sometimes we do have the energy just jump into something. I think we call it radio. Sometime we need to 'guide' and 'squeeze' the energy to make it go where we want and do what we want, that's why we need the amplifier and wires.

 

The problem with that is you are building the wrong mental picture of matter being the carrier of ENERGY and it's very hard to unlearn an incorrect first impression. It's usually best IMHO just to say 'this is the way it is' until they gain a good foundation of facts.

I'm not sure picturing matter as a carrier of energy is all that bad. When two cars crash head-on aren't the cars the carriers (transmitters/receivers) of all that suddenly released/transferred energy?

But more importantly... Exactly what should I say to the kid? Here's my description (repeated from an earlier post for convenience):

"You strum the guitar and the movement of the metal strings through the magnetic field around the pickups
makes the electrons run back-and-forth through the wires. The faster they change direction, the higher the note (pitch, frequency).

"These wires are connected to the gate (grid) in the middle of the tube, and this back-and-forth movement of electrons opens and closes that gate. When the gate is open, a whole bunch of electrons run upward from the pool at the bottom of the tube, through the gate, and out the top.

"The (anode) resistor prevents the electrons from escaping too quickly back into the electron pool (ie, ground via the power supply), so the electrons alternately bunch up (and un-bunch up) against the capacitor's "rubbery wall" (as the gate in the tube opens and closes). This causes the electrons that are sitting on the other side of the capacitor's rubbery wall to move back and forth in sync with the ones from the guitar. Only there's more of them. And they move in the opposite way (180 degrees out of phase).

"Ditto for the power amp stage, only we leave out the resistor and let the electrons rush back to the pool as fast as they can because (a) the wire in the transformer is itself a kind of resistor, and (b) the varying concentration in that wire is enough, all by itself, to generate the back-and-forth electron movement we need on the secondary side of the transformer to make the speaker -- which in a lot of ways is the opposite of the guitar pickup -- wiggle in sync with the strings.

What would you say instead?

 

I'm not sure picturing matter as a carrier of energy is all that bad. When two cars crash head-on aren't the cars the carriers (transmitters/receivers) of all that suddenly released/transferred energy?


"These wires are connected to the gate (grid) in the middle of the tube, and this back-and-forth movement of electrons opens and closes that gate. When the gate is open, a whole bunch of electrons run upward from the pool at the bottom of the tube, through the gate, and out the top.

"The (anode) resistor prevents the electrons from escaping too quickly back into the electron pool (ie, ground via the power supply), so the electrons alternately bunch up (and un-bunch up) against the capacitor's "rubbery wall" (as the gate in the tube opens and closes). This causes the electrons that are sitting on the other side of the capacitor's rubbery wall to move back and forth in sync with the ones from the guitar. Only there's more of them. And they move in the opposite way (180 degrees out of phase).

"Ditto for the power amp stage, only we leave out the resistor and let the electrons rush back to the pool as fast as they can because (a) the wire in the transformer is itself a kind of resistor, and (b) the varying concentration in that wire is enough, all by itself, to generate the back-and-forth electron movement we need on the secondary side of the transformer to make the speaker -- which in a lot of ways is the opposite of the guitar pickup -- wiggle in sync with the strings.

What would you say instead?

It's not a bad analog when explained because while cars are not electromagnetic energy a major force that binds the materials together in cars is the electrostatic force half of the EM field. The kinetic energy of the crash breaks or shears the bonds causing the material to deform, heat, break, fly off and fall back down due to gravity and friction. All the matter is still there but the energy is dissipated.

For the grid it's the electric field on the grid that modulates the plate current. The electrons are the carrier of charge that develops a voltage from charge separation in the tube from the grid to cathode.

The anode resistor/capacitor membrane is not too bad. I like the capacitor's 'rubber wall' analogy as long as it's understood that the total amount of electrons never changes and are pushed about the circuit from one side to the other.

I think that 'pool' is poor choice of words to use. Pool implies there is a reservoir or stockpile of electrons in the power supply that gets refilled somehow from the power plug. The total number of electrons in the amp as a whole never changes just like the number of electrons in the capacitor as a whole doesn't change. What does change is the distribution of electrons (charge separation from actual slow/tiny movements of electrons and the quick movement of electrons in the tube) over time and space in the tube, power supply and components from the driving force of the EM fields and the electrons as a system.

I think this is a primary factory in confusion at times when people try to look at electrons or volts or currents or even fields in isolation. They all are important but intimately interconnected. To explain the transformer action with only electrons is impossible. You must talk about the generation of a magnetic field from the movement of charge (electrons) in the wire and how that coupled magnetic field (the carrier of energy) causes charge (electrons) on the secondary wire to redistribute charge over the length of the wire in response and develop a voltage potential and current to the load (speaker) as power.

I know it sounds complex and it is but you don't need complex math or concepts to understand it (You do need that to engineer and build things). If it was easy anyone could do it with a few hours training and I couldn't afford my outrageous vacations every year.

 

...to explain the transformer action with only electrons is impossible. You must talk about the generation of a magnetic field from the movement of charge (electrons) in the wire and how that coupled magnetic field (the carrier of energy) causes charge (electrons) on the secondary wire to redistribute charge over the length of the wire in response and develop a voltage potential and current to the load...

Let's picture the primary and secondary of the transformer as two rows of line-dancing electrons facing each other. When the primary row moves ("to the left, to the left, to the right, to the right"), the secondary row moves in sync. Why? Because the secondary dancers see which direction the primaries are moving, and hear the beat made by the stomping of their feet. (The visual component is the direction vector of the field, while the auditory component describes both the frequency and amplitude of that field).

We can take the analogy further: if there are twice as many dancers in the secondary line, there will be twice as much activity (energy) in the secondary line; and vice versa.

And more: if the dancers are connected to each other by close proximity, they'll be able to better see what the others are doing and will thus respond more rapidly and precisely.

And still more: if they're connected via a common and somewhat "flexible" dance floor (core) they're feel the beat more strongly and will respond, again, more rapidly and precisely.

I especially like this analogy because line dancers (electrons) are naturally assumed to be more tangible than light waves and audio vibrations (the field); yet the kid is no doubt familiar with the way sights and sounds can affect the action of physical beings.

My goal is to develop a consistent metaphorical description the entire circuit, using the same kind of images throughout. (I don't want to use line dancers in one place, water-filled pipes in another, etc.) I want to pick the best analogy and put it to work everywhere. I'm starting to lean toward the line dancing electrons as the main characters in the story...

 

I know it sounds complex and it is but you don't need complex math or concepts to understand it (You do need that to engineer and build things). If it was easy anyone could do it with a few hours training and I couldn't afford my outrageous vacations every year.

My motto has always been, "First do, then understand." And I've often been surprised by how far one can get without really knowing what one is doing! See the attached PDF for an example.

 

My goal is to develop a consistent metaphorical description the entire circuit, using the same kind of images throughout. (I don't want to use line dancers in one place, water-filled pipes in another, etc.) I want to pick the best analogy and put it to work everywhere. I'm starting to lean toward the line dancing electrons as the main characters in the story...

For young children that's very good if you can also have the dancers move in random patterns each around a small spot at first when there is no music so show the electrons are always in motion and it takes music (fields) to make them dance and move together in a pattern.

For older children (10ish) it's not something I would do as most children by then understand at least the simple magnetism of attraction and repulsion so while using metaphor/analogy is ok, it should be explained as a way to keep it interesting and fun as we explore possibilities of all those boring facts once they understand the correct terms but shouldn't be a way to teach them the facts.
Personally I like my metaphors in Shakespeare not in science as it quickly turns into arguments about philosophy instead of facts.
http://groups.psych.northwestern.edu/gentner/papers/GentnerJeziorski93.pdf
http://www.nature.com/news/2011/110223/full/news.2011.115.html

 

For young children that's very good if you can also have the dancers move in random patterns each around a small spot at first when there is no music so show the electrons are always in motion and it takes music (fields) to make them dance and move together in a pattern.

I'm liking the "line-dancing electrons" more and more: everybody already knows that dancers tend to "mill around" on the dance floor while waiting for the music to start, so they won't be surprised to hear that electrons do the same.

For older children (10ish) it's not something I would do as most children by then understand at least the simple magnetism of attraction and repulsion so while using metaphor/analogy is ok, it should be explained as a way to keep it interesting and fun as we explore possibilities of all those boring facts once they understand the correct terms but shouldn't be a way to teach them the facts. Personally I like my metaphors in Shakespeare not in science as it quickly turns into arguments about philosophy instead of facts.

Allow me a quote from C. S. Lewis: "ALL language, except about objects of sense, is metaphorical through and through. To call God a "Force" (that is, something like a wind or a dynamo) is as metaphorical as to call Him a Father or a King. On such matters we make our language more polysyllabic and duller: we cannot make it more literal. The difficulty is not peculiar to theologians. Scientists, poets, psychoanalysts, and metaphysicians are all in the same boat."

The experience you described earlier with the magnet dropping through different kinds of pipes was an attempt to give your daughter a sensual experience of something that can only be described metaphorically. The sensual feeling that a kid gets when he holds two magnets in proximity can be described literally using words like "push" and "pull" because the effect is indeed sensual. But the cause of those sensual experiences can only be described metaphorically.

Just look at the various definitions of the word "field" in a dictionary (from "a piece of land cleared of trees" to "space around a radiating body within which its electromagnetic oscillations can exert force on another similar body not in contact with it") and note how the initial definition is a literal description of something that can be sensed, and how all the others are metaphorical applications and extensions of that original.

By taking the "color" out of our descriptions we often feel that we are being more precise and less childish. But what we're really doing is making our descriptions less complete and, in every sense of the term, less sensible. Good metaphors -- and we must have metaphors -- appeal to common objects and experiences of sense. "Except you become as little children," Somebody once said, "you're going to miss all the important stuff." I'm paraphrasing, of course.

 

By taking the "color" out of our descriptions we often feel that we are being more precise and less childish. But what we're really doing is making our descriptions less complete and, in every sense of the term, less sensible. Good metaphors -- and we must have metaphors -- appeal to common objects and experiences of sense. "Except you become as little children," Somebody once said, "you're going to miss all the important stuff." I'm paraphrasing, of course.

IMHO
The problem is the description of electricity is mathematically precise, is a unique force of nature that requires a knowing a vocabulary of things that are not intuitive and have no true common objects or experiences at first. Building your electrical intuition on primarily on analogy and metaphor is the road to hell in science until you know the subject cold (like a Scientist) and need to extend into the unknown. IMO the current method teaching electricity and electronics with moving electrons as a core point for interaction is wrong because most of us get to a point were we see it's Bullcrap. I'm not saying you can't teach this way but I think it stunts your ability to later see the root cause of problems in electronics. Some people take longer than others but eventually the analogies all fall apart and you need to restart the process at a more basic level so why not start correctly at the beginning with a good beginners book that I wish I had growing up.

http://amasci.com/miscon/elteach.html

I didn't start with analogy and metaphor on my journey in electronics. I had an old book from 1943 that a long forgotten uncle left at my grandmothers house as my first experience into the working of electricity. It was filled with mysterious words about wires, batteries, circuits and tubes. I had plenty of open space in my head waiting for something to fill it so why not read it. I first read the book understanding almost nothing (and that made me want to understand it) but because it was a reference book I could find out what the words described. Having visions of dancing electrons in my head would not have helped but taking the mental effort to build the foundation of correct terms and images for the words did.

I still have the book and treasure it greatly.



http://www.amazon.com/Drakes-Cyclopedia-Radio-Electronics-Edition/dp/B005EEHLGS

 

...Building your electrical intuition on primarily on analogy and metaphor is the road to hell in science..."

And yet you recommend:

...a good beginners book that I wish I had growing up. http://amasci.com/miscon/elteach.html

Which takes us to ( http://amasci.com/redgreen.html ) where the author attempts to explain "some basic electricity concepts" using red and green semi-transparent sheets laid on top of each other. "Ordinary matter," he says, "is actually composed of equal quantities of positive and negative charge. The red plastic sheet represents the positive part of matter, and the green represents the negative. In everyday matter, the positive and negative charges are equal, so they cancel each other out, and the matter has an overall electric charge of zero. The plastic sheets illustrate this: when we combine the red and green, the result is colorless black."

How is this any less metaphorical than line-dancing electrons?

I didn't start with analogy and metaphor on my journey in electronics.

But of course you did; only you've forgotten or didn't notice then or now. How do I know? Because ALL language (except that tiny portion that describes sensual experiences) is metaphorical by definition and necessity. It's simply a matter of which metaphors are used. I don't have a copy of Drake's so I can't point out the specific metaphors he used, but I am certain the thing is full of them.

 

And yet you recommend:

How is this any less metaphorical than line-dancing electrons?

Yes, because because he talks about electrical charge not matter. The property of the electron that make them important electrically is not their matter and how it moves, it's their charge.

But of course you did; only you've forgotten or didn't notice then or now. How do I know? Because ALL language (except that tiny portion that describes sensual experiences) is metaphorical by definition and necessity. It's simply a matter of which metaphors are used. I don't have a copy of Drake's so I can't point out the specific metaphors he used, but I am certain the thing is full of them.

Absolutely not, I was completely dumbfounded by that book. That book is a reference book with just the facts from cover to cover. It was not designed to teach electronics or electricity. The original was from 1923 (I have the 11th edition), long before the touchy feely age of today. I learned from the book in the old fashioned way school was taught then and it was the same for most of my military instruction. I memorized the basics first without understanding by reading it again and again until it knew the words then it memorized the information about those words until I could read that gibberish without stopping every 10 seconds. It took quite some time for it to connect and to have that click to the next level that meant real understanding.

I was motivated to understand. I think that motivation is a very important factor in learning and is far more important than 'Syntactic sugar'. In the military the motivation for learning electronics was easy, learn this -> have a nice job, don't learn this -> mop floors or dodge bullets for years.

My hardest subject in the military had nothing to do with electricity or electronics. It was typing and the ability to type while doing several things simultaneously while still perfectly typing coded text that was impossible to guess the next letter or word in the dark or blindfolded for like 5 min at some constant WPM rate. It was was one of those things you had to master or fail the course even if you were a genius at electronics (I was the Radioman that also repaired equipment that the official 'Electronic Techs' never saw due to the required security clearence). So we sat in the typing room day after day for 8 hours typing on teletypes with no characters on the keys to a ticking metronome pressing one key then another to a displayed character until we could to all of them. Then we were given pages of 5 letter code group messages to type until we could do it perfectly in sync to the metronome tick. Then they would speed up the ticks faster and faster until you stopped thinking about the mechanics of typing consciously and started to see first one group mentally then several groups and finally whole lines in your short term memory as a buffer so you could listen to a voice or code in one ear on the radio intently and type while talking to another person about what was happening.
It was shocking to me to see my hands move without conscious thought at first but it was an important lesson about how the boring repetition of information can allow you to see things and work detailed problems in your subconscious mind while your conscious mind handles the big picture.

I know that guys look while the type was graded.
https://research.archives.gov/id/558536

NSFW language but at 09:50 in the video he talks about the typing class.

 

I don't have a copy of Drake's so I can't point out the specific metaphors he used, but I am certain the thing is full of them.

Absolutely not... That book is a reference book with just the facts from cover to cover.

I'm afraid we're going to end up agreeing to disagree. But I'll give it one more try. I've still not been able to find a copy of Drake's to quote, but I'm sure that somewhere it has a diagram like this:


And I'm sure that he says that is a triode. And when he does, he's speaking metaphorically, not literally. He's saying, in effect, "This is not a triode, but a triode is something like this." In other words, he's not just giving you "the facts," but a way of picturing those facts as well. I'm equally sure that in other places he draws "word pictures" for you -- pictures without actual graphic representations on the page but which are, nevertheless, conjured up in the reader's mind. In short, the metaphors are there, you're just not seeing them.

Perhaps you've seen this rather famous painting by Rene Magritte:



The French at the bottom translates as follows: "This is not a pipe." Get it? Unless you've got the actual thing in your hand (or eye or ear or nose or mouth), you can't talk about what you've got except by speaking metaphorically. I repeat my quote from Lewis: "ALL language, except about objects of sense, is metaphorical through and through... we can make our language more polysyllabic and duller: we cannot make it more literal."

The bottom line is this: If we're going to teach electronics, we're going to teach electronics metaphorically because the critical things we're dealing with are not objects of sense. We don't have the option of teaching "just the facts". We're forced, by the nature of our minds and our language, to use symbols, analogies, similes and metaphors throughout. So the question isn't whether it's a good idea to teach electronics metaphorically (or not). The question is simply, Which metaphor(s) are most helpful to the student?

 

No he is not speaking metaphorically, he is speaking of a language you need to learn to understand.

You have displayed (part of) an engineering drawing of a triode that looks remarkably like Fleming's original.

The difference between a metaphor and an engineering drawing is that the whole purpose of an engineering drawing is to contain enough information (for the reader) to be able to construct the object concerned.

Metaphors do not meet this requirement in general.

 

I have learned a few things lately. Apparently, "internationally defined current" is a "charge" or "energy" that flows from the positive supply terminal to the negative supply terminal. So, when you speak of current, you have to work within the convention that current flows from positive to negative. This definition has nothing to do with how or whether electrons jump off a heated cathode and move toward the positively charged terminal. Electron flow still exists, you just can't call it current in a court of law.

 

you just can't call it current in a court of law.

I wonder just how many times the direction of current/electron flow has actually been discussed in court proceedings. Zero?

 

I wonder just how many times the direction of current/electron flow has actually been discussed in court proceedings. Zero?

LOL! Instant mistrial!

 

Because my original academic education as far as electronics was concerned occurred in the valve/tube era I am just glad that my original tutors taught me electron flow per cathode to anode.
I do now generally use conventional flow, just because drawing and schematics are 'conventionally' drawn this way, But the knowledge I have acquired in using both methods total does not cause any confusion for me so basically it is of little or no consequence in labeling one 'right' or 'wrong'.
Max.

 

Same for me. I can think or do math in either model without having migraine headaches or red faced public arguments. Apparently I lack the gene for demanding that everybody do it one way only.

 

I'm afraid we're going to end up agreeing to disagree. But I'll give it one more try. I've still not been able to find a copy of Drake's to quote, but I'm sure that somewhere it has a diagram like this:
...
And I'm sure that he says that is a triode. And when he does, he's speaking metaphorically, not literally. He's saying, in effect, "This is not a triode, but a triode is something like this." In other words, he's not just giving you "the facts," but a way of picturing those facts as well. I'm equally sure that in other places he draws "word pictures" for you -- pictures without actual graphic representations on the page but which are, nevertheless, conjured up in the reader's mind. In short, the metaphors are there, you're just not seeing them.

We both agree that Symbolic Abstraction (a superset of facts, theory, metaphor, or complex analogy) (just metaphor is just the wrong term in this case) is needed in a reference book to store information instead of actual tubes and resistors the same way it's needed in our brain. That's the power of symbolic abstraction, by using a picture of a tube we develop the mental patterns needed to represent the basic information needed to connect that type of tube to other components without the baggage of each tiny detail so we can compartmentalize our thought process to see the important aspects of the circuit.

So in this case the book is saying this picture is literally a symbolic triode not a metaphorical analogy to a triode like a water valve.

Which metaphor(s) are most helpful to the student?
The ones that convey concepts and explanations not the actual facts. Facts should to be first learned literally if possible then we can build a symbolic relationship with the physical or mathematical axiom to the abstract so we can communicate in words and pictures about those facts.

In my mind I don't think metaphorically about electronics because there's no need. I know the correct symbols, have the correct mental patterns to interconnect those symbols in the subconscious mind so in my conscious mind I see the physical image of the entire board or object after study and can mentally zoom into details while the subconscious generates the needed patterns of those zoomed details in my head.

I believe a large number of people in this field don't think metaphorically about it unless forced to and using that method for those that don't when they are young is counterproductive in engineering.