But how SHOULD we teach kids about 'electricity'?
1997 William Beaty, BSEE
This is the one thing I lack, good replacements for the incorrect
material in K-6 textbooks. I'm not a teacher, so I lack the experience in
teaching children. I would need experience to create *good* curriculum
material. In the following, keep in mind that I'm an EE (electronics
designer) who complains about the accuracy of info in grade-school
textbooks, but
without having the benefit of actually being an educator USING any of
these textbooks while teaching.
Note that the problem with electricity misconceptions is mostly in K-6
texts and children's books. In my experience it seems limited to
technician training material, as well as
highschool grades and
earlier. For good and reliable information , textbooks at or above the
undergraduate college level are almost uniformly accurate. Unfortunately
they all base their explanations on mathematics, and would require
'translation' before children or the public could understand their
material. (And that's what my electricity website provides:
translating college-level physics textbooks into everyday
language/pictures/concepts which anyone can understand.)
I've only found one popular Electricity book which lacks nearly all the
"infectious" misconceptions. Unfortunately it's out of print.
"Basic Electricity
JE-101" by Gene McWhorter
It seems to be aimed at the middle high school level. It even
has quizzes at the end of chapters. Unfortunately Radio Shack replaced it
with "Basic Electronics", which lacks all the wonderful visual
representations of beginning electrical science found in the eariler book.
For a K-12 classroom textbook which is far above average, try Prentice
Hall's "Science Explorer" series, the volume on Electricity
and Magnetism by Dr. C. Wainwright of the excellent CASTLE project.
This one dates from 2007, and lacks the misconceptions I
discuss on this site. I don't know if other Prentice Hall editions lack
the errors, since Wainwright isn't the author, and few authors are aware
of the textbook misconceptions problem (or aware of their own.)
For high school level, an excellent commercial curriculum package is the
CASTLE material. It
takes a conceptual approach to electricity education, and is widely used
in high
school physics classes. It concentrates on charge flow and energy
transfer concepts, and doesn't contain all the misleading "electricity"
contradictions. The required kit of parts is sold by Pasco.
Here's an online copy of the
student manual.
For K-6 grades there's also the old ESS "
BATTERIES AND BULBS" lesson plan
from ESS and Delta Education, ISBN 0-87504-011-X. It's been
around since
about 1986 and is excellent.
My own attempt at some visual/conceptual introductory material is here:
Explaining "electricity" with red/green plastic sheets.
If I were teaching, I'd concentrate on initially having the kids play with
all sorts of real electrical devices. Batteries and bulbs, tiny motors,
loudspeakers, maybe solar cells and LEDs (easily found at Radio
Shack.) A secret:
buy lots of "clip leads", wires with little alligator clips on each end.
This lets you connect various devices together, even if the devices lack
proper connecting terminals.
One particularly wonderful device is the "Genecon" hand-cranked generator,
available by mail order from Arbor Scientific among others.
(www. arborsci.com)
It puts out about 8 volts DC max, and the polarity
will reverse depending on direction of cranking. Unfortunately it costs
over $50 each
or so. Maybe too expensive to have 30 of them for the entire class!
Look around and you can find
other types for less than
half the price.
At the very least, consider buying a single generator to play
with.
Here's an electronics education secret: sometimes you can find digital
voltmeters for well under $10 (even under $5 if on sale,) check out
the multimeters
at Harbor Freight Tools. Our city has a couple of those stores, so
maybe yours does too (avoid mail-order shipping.)
Once the kids have had fun and maybe are starting to get excited about
the mysteries in the wires, only then start on the more standard
curriculum material.
For explaining how charge-flow and electrical energy works, my favorite
simple demo is two
clothesline pulleys and a loop of rope (with rope ends butted together and
duct-taped.) This "rope-ic circuit" shows how the electric charges in a
metal can be forced to flow in a circle. Drive one pully into motion with
your hand, and that pulley becomes a generator. The other pulley is
driven by the flowing rope, and it behaves as a motor. To demonstrate an
open circuit, have one person turn a pulley, and have another person grab
the the rope at some point in the loop and hold it still. To illustrate
an electric heater or electric light bulb, let the moving rope rub against
your
thumb so your thumb gets hot. Or, to illustrate Alternating Current, turn
one wheel rapidly back and forth to demonstrate how AC circuits contain
charges which sit in one place and wiggle back and forth, while energy is
still communicated to all parts of the loop.
If you can afford to buy a bunch of $4.00 clothesline pulleys, perhaps you
can even have the kids expand it into a vast network of wheels connected
by a single loop of string, all of which will turn when a single wheel is
turned, and all of which will stop when the "circuit is opened"; when the
string is grabbed in one place. (I haven't tried this myself. Don't know
how easy it is.) The cellulose molecules in the rope can represent the
electrons in a wire. Flow of the rope represents charge flow in wires.
The push/pull tensions in the loop of rope represent electric voltage.
The slow speed of the rope matches the slow speed of charge flow.
The rapid transmission of "horsepower" from pulley to pully represents
the electric energy which moves at nearly the speed of light in circuits.
To show that electrons aren't so invisible, replace the loop of string
with a loop of fishline. When you turn the pulleys, the fishline appears
not to move (since it's very smooth.) Similary in wires, the charges are
visible as a silvery metallic color (all metals have this), but when the
charges all begin to flow along, we cannot see the silvery stuff start
moving (since it is far too smooth, it has no marks which might show that
it's flowing!)
Another similar "visible electricity" demo would be a circle of railroad
track and a bunch of freight cars as the "electrons" (With no engine of
course). Include enough freight cars so that you cover the entire circle
of track. Then push one freight car along, and you transmit kinetic
energy almost instantly to all the cars in the loop. The cars represent
the copper's electrons which flow within a wire. Or, put a row of marbles
in a circle on top of a large steel coffee can. If you can get hold of a
bag of old golf balls, maybe you can fill a circle of model railroad track
with large rolling "electrons" (N-gauge track might be needed, I don't
know if golf balls will hit bottom on the standard HO-gauge track). Fill
the entire track with balls, so when you push one ball, all balls must
roll at the same time like a big flywheel.
Other stuff:
Here's a big problem. All modern circuitry is based on voltage
signaling and voltage-based
power supplies. Not current. Yet in grade-school textbooks, all their
voltage explanations are instead labeled as "static electricity."
Claimed to be a "kind" of electricity we don't use, while supposedly
Current is the only important thing. In fact it's the very
opposite. And, we teach all about magnetic fields, but pretend that
e-fields don't exist, and kids never hear about them. Yet e-fields are
the driving force behind our
entire technical civilization. So, any curriculum
needs to have voltage, electric force or "pressure," at its very center.
Or, at the earliest grades, everything needs to be laying a groundwork for
"Future Explanation of Voltage."
For earliest grades, my usual suggestion is to abandon the terms
"electricity," "current," and
"power," and instead start out
with simpler terms, only using as much correct terminology as you think is
appropriate for that age level.
- We do not study "electricity", we study "electrical science."
- "Electricity" doesn't flow inside metal wires, charges do.
- Electrical science isn't based on electrons, it's based on charges.
Yes, in metal wire it's mobile electrons, but in battery-acid its mobile
protons, and in dirt and in human flesh it's mobile sodium and chloride.
To avoid getting into the details, just call them "charges,"
positive and negative.
- Generators don't produce "electricity", they produce the electric
pumping force. They also send out "electrical
energy" which is made of invisible fields resembling radio waves
that whiz along outside of the wires. Generators are charge pumps.
They force the charges found inside the wires to flow along.
- Batteries don't supply "electricity", the wires do. A battery is a
chemically-fueled charge pump. Like any other pump, a battery takes
charges in through one connection and spits them out through the other. A
battery is not
a source of the "stuff" being pumped. When a battery runs down, it's
because its chemical fuel is exhausted, not because any charges
have been lost. (Remember that a battery is just a Fuel Cell, but
it keeps its chemical fuel on board.) When you "recharge" a battery,
you are forcing charges through it backwards, which reverses the
chemical reactions and converts the waste
products back again into chemical fuel.
- Light bulbs don't consume "electricity." Instead, the charges of the
thin filament all flow along much faster than they would in
thicker wires,
and this heats the filament because of a sort of "electrical friction".
Charges are forced into the bulb through one terminal, but then they all
flow
back out again through the other terminal. The quantity of charges inside
the filament doesn't change, and none are used up.
- As Michael Faraday discovered in 1839, there are no different "kinds"
of electricity. Faraday states that only one kind exists, and the various
supposed "electricities" are just situations where magnitudes of
net-charge and charge-flow take on various values. There aren't many
electricities, instead the topic of Electrical Science is divided into
many subtopics such as "Electrostatics," "Electrochemistry,"
"charges," "current," "imbalanced charge," "sparks," even "voltage".
In other words, "current electricity" doesn't actually exist, and neither
does "static electricity."
See what Faraday says about this.
Also see the electricity map for the
fuzzy boundary between so-called "static" and "current." It's all just
one thing, but humans divide it up into fields of science called
"bioelectricity," "electrostatics," etc.
- Avoid saying "static electricity" and "current electricity". Instead
call them "charge imbalance" and "charge flow", or possibly "voltage" and
"current". (A little known fact: static electricity involves high
voltage. Also, during electric currents in high-voltage circuitry, even
the flowing charges
will
always display all of the the familiar "static electricity" effects.
Doesn't this mean that "static" electricity can move along?!! Nope, it
just means that "static" electricity isn't about something remaining
motionless.
It's about high voltage, with or without an electric current.)
- Perhaps even avoid saying "Current." After all, "current"
doesn't flow
in wires; charges do. Since the term Electric Current
means the same thing as charge-flow, just simplify the lesson by talking
exclusively in terms of charge-flow. (Analogy: when explaining water, we
talk about water, rather than saying "current" this, and "current" that.
And in pneumatics and air pumps, we don't insist that everything is based
on "wind" or air-current; if we mean flowing air, we just say "flowing
air.")
I've learned an important lesson from the "new math" debacle in the late
1960's. I don't want to become one of those experts who causes problems.
As an educator, I have too much theory in my head and not enough teaching
experience. If I were to write a K-6 science book, that book might appeal
more to academics and engineers than to children and educators.
Curriculum material should be created by teachers, not by
content
experts having only months of classroom experience.
If anyone should figure out more good techniques, lesson plans,
activities, etc., then by all means get them onto the WWW so other
educators can benefit. We can point our "Electricity" websites at each
other.
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