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  #1  
Old 07-15-2010, 06:42 PM
Arnold Winkelried Arnold Winkelried is offline
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Help me explain electricity to children (age range 4-12)

Sunday school at my church is doing a science curriculum for this summer. I signed up to show off a glowing pickle and potato battery on Sunday (in three days.)

Here are my questions:
Keep in mind that the class will have a group of kinds in varying ages, the youngest being 4 and the olderst around 12 or 13.
1) What is the best way to explain electricity in simple terms?
2) How do you explain in simple terms why it is very bad to handle an electrical motor while you're standing in the bathtub?
3) What is the simplest way to do the glowing pickle experiment? Several websites have said that it can be dangerous, and I've been told that the acceptable casualty rate for my demonstration is 0 - all children have to be alive at the end of the demonstration.
4) Any tips on the potato battery experiment to make it more interesting?

Keep in mind that my presentation should not take more than about 45 minutes.

Also, the lessons are supposed to be demonstrating the "scientific method" (somewhat akin to Mythbusters): we present a myth, test it, see if the myth is true or not. In my case, the myths would be: a potato can produce electricity! (and) a pickle can be used as a lightbulb! (I would like to have a counterexample: the potato can produce electricity, but this vegetable won't work. A pickle can be used as a lightbulb, but an eggplant cannot. That kind of thing.)

P.S. I wasn't sure whether to put this in IMHO or GQ.
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  #2  
Old 07-15-2010, 07:00 PM
johnpost johnpost is online now
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you shouldn't be doing a glowing pickle for children. that in itself is with some danger.

most significantly children of that age don't have a sense of safety or of cause and effect. no matter what you say otherwise someone might be tempted to try something similar or another child they relate the experiment to (without cautions) will try it.
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  #3  
Old 07-15-2010, 07:50 PM
matt_mcl matt_mcl is offline
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Or as my physics teacher used to say jovially, "Do not touch this. It will kill you. You will die."
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Old 07-15-2010, 08:06 PM
rowrrbazzle rowrrbazzle is online now
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Quote:
Originally Posted by Arnold Winkelried View Post
I would like to have a counterexample: the potato can produce electricity, but this vegetable won't work.
Since the electricity really depends on the electrodes (as I'm sure you know), some vegetables/fruits other than the potato will work. The aforementioned pickle will, and in fact so will the brine by itself (test a cucumber, too). Show them all that, and show that having both electrodes of the same metal won't work.
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  #5  
Old 07-15-2010, 08:27 PM
RaftPeople RaftPeople is offline
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I recently read some article about what is really going on with electricity and it bugged me that I had always been taught a simple version without anyone hinting that the simple version is really just a way to think about it.

Might be worth mentioning that someday they may want to investigate how bizarre it really is. Just a thought.
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  #6  
Old 07-15-2010, 08:47 PM
Mijin Mijin is offline
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I think one of the analogies of water in pipes or marbles in a tube, and then explaining things like lightbulbs, capacitors etc in those terms, might be helpful to the whole audience.
Just generally helping with their intuitive idea of electricity...about all you can do for that range of ages.
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  #7  
Old 07-15-2010, 09:29 PM
Magiver Magiver is offline
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the best way to demonstrate how dangerous electricity is to flesh is to cook a hot dog using regular house current.

This is your brain, this is your brain on drugs electricity.

You can insert innocent penis joke with the kids by asking them what it would do to their willy.
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  #8  
Old 07-15-2010, 09:49 PM
Mr. Duality Mr. Duality is offline
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When my kid was about 3 years old I showed her a (mostly) depleted 9 volt battery which had been in a smoke detector for a year. I explained that the battery had just a little bit of electricity in it, and the wall sockets have a lot of electricity. Then I touched the battery terminal to my tongue to show her it was OK to do so, and had her touch the terminals with her tongue. She received ed a small shock and has never had an urge to stick a anything other than a plug in a wall outlet.
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  #9  
Old 07-16-2010, 06:00 AM
t-bonham@scc.net t-bonham@scc.net is offline
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Teaching science at a church Sunday school? Seems counterproductive.
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  #10  
Old 07-16-2010, 07:22 AM
Machine Elf Machine Elf is offline
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Quote:
Originally Posted by johnpost View Post
you shouldn't be doing a glowing pickle for children. that in itself is with some danger.
As long as the kiddies don't touch it, there shouldn't be a hazard. The worst that will happen is if you push the wires in so far that they make direct contact with each other inside the pickle; you'll get a good "pop" right before the circuit breaker blows.

I did the pickle trick a number of times in grad school. typically there was a lot of beer involved, but nobody died. Easiest way:

1. Snip an electrical cord from a dead appliance.

2. Strip an inch of insulation from the ends of the two wires.

3. Twist the wire ends tightly (not to each other). They need to be stiff enough to pierce the ends of the pickle. If you've got small-gauge wires, consider tinning them with solder to stiffen them.

4. Get a moderately-sized pickle.

5. Push the wire ends into the pickle, one at each end. Insert the wire all the way up to the insulation.

6. Place pickle on plate. Dim the room lights.

7. Do not touch the pickle during this step. Plug the cord into a wall socket. Pickle should start to flicker/glow/steam. Enjoy the effect for maybe 15-20 seconds. If flickering fades, you can jiggle the wires to get better contact inside the pickle, but again, do not touch the pickle during this step.

8. Unplug the pickle.

Make it a point to tell kids they absolutely should not do this on their own without their parents present.

I'm with Raftpeople: any model that is simplified enough for little kids to understand is going to be wrong enough to hobble deeper understanding when they get older, but it'll get them to the point where they understand ideas about forming a complete circuit, grounding appliances, and safety. Let them know there is much more to the nature of electricity than you can tell them in one day, and that they can find out more as they get older. Encourage them to take advanced science classes in school.

Mr. Duality's battery trick sounds like a useful demonstration, but there might be sanitation issues associated with having a large group of kids lick the same pair of battery terminals. You might suggest they do this on their own - or if it's not too big a group, give everyone their own battery.

Explaining the dangers of holding an e-motor while standing in a filled bathtub? Once they understand the idea of completing a circuit, and the idea of electricity flowing from a high-voltage line to a low-voltage line/ground, explain that electricity likes to take the path of least resistance. Your explanation at that point is going to go a bit beyond electricity and into risk management: if they hold an e-motor while standing in a tub, they will probably be absolutely fine, but there is a small chance of a problem inside the motor that could electricify the case, sending current through their body to ground (easier/less resistance than going through the motor windings). Or they might accidentally drop the motor into the tub, and if they're standing between the motor and the tub's drain pipe, current might pass through them. And although that chance is small, the consequences could be fatal. A GFI outlet will probably protect them, but there's a small chance it won't, again with disastrous consequences. Explain that it's not a good idea to deliberately rely on safety mechanisms; their first line of defense is being smart/careful, and the safety devices (grounding, GFI circuit breakers) are only there to back them up during real, honest mistakes.

Low voltage, e.g. batteries, can't easily electrocute a person, but if it's capable of delivering a lot of current, then a short-circuit can produce a lot of heat in a short time and cause thermal burns and other shenanigans. Classic example: accidentally dropping a wrench across the terminals of a car battery. BIG BRIGHT spark, LOUD pop, and the evolved hot gases at the arc site may blow your wrench across the garage.
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  #11  
Old 07-16-2010, 07:59 AM
Francis Vaughan Francis Vaughan is online now
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I'm going to the second the advice/admonition to on no account demonstrate the pickle. There is simply just too high a risk that a kid will decide to try it themselves. Maybe only a chance in a thousand, but across the planet that is a lot of 5 year old kids stripping the insulation off mains cord. Sooner or later one of them will die.

The potato is more chemistry than electricity.

Teaching scientific method with these demonstrations is stretching things a bit really. The classic method involves a falsifiable hypotheses. That means teaching a logical deduction.

Personally, if I were demonstrating electricity to this age group I would go for electromagnetism. You can do the whole run from permanent magnets, to electromagnets and get as far as building a working motor from a cork, a few pins and some wire in 45 minutes. As a demonstration to inspire, the motor is almost unbeatable.
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  #12  
Old 07-16-2010, 08:42 AM
robby robby is offline
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Quote:
Originally Posted by Arnold Winkelried View Post
Here are my questions:
Keep in mind that the class will have a group of kinds in varying ages, the youngest being 4 and the olderst around 12 or 13.
1) What is the best way to explain electricity in simple terms?
Back when I was teaching introductory physics, one of the best resources I ever came across for simple explanations of electricity were the articles written by the SDMB's own Bill Beaty. I would start here.
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  #13  
Old 07-16-2010, 10:50 AM
notsoheavyd3 notsoheavyd3 is offline
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Quote:
Originally Posted by robby View Post
Back when I was teaching introductory physics, one of the best resources I ever came across for simple explanations of electricity were the articles written by the SDMB's own Bill Beaty. I would start here.
Kick-*ass, he even talks about the "speed of electricity". (I think I mentioned that when I was in high school we had some guy do an electricity demonstration. In it he claimed it would take minutes for your lights to go on if we used DC which is utter nonsense.)
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  #14  
Old 07-16-2010, 12:51 PM
YogSosoth YogSosoth is online now
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Give them a fork and point to an outlet
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  #15  
Old 07-16-2010, 01:06 PM
iamthewalrus(:3= iamthewalrus(:3= is offline
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Make a little breadboard with clearly delineated wires, a few batteries, a few light bulbs, and a bunch of switches.

Explain that electricity flows between one end of the battery and the other, but that it will only go through certain things, and that there has to be a connection.

Flip some switches to route different paths in. Put some lights in series, and some in parallel, and show how it's stronger or weaker in those cases. Totally safe, explains circuits, and it's got cool buttons and switches that they can take turns volunteering to press.
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  #16  
Old 07-16-2010, 01:44 PM
UncleFred UncleFred is offline
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I believe The Master once described a little game for kids called "Shaking Hands With Jesus" (can't find the link) that would have taught the lesson.

But don't try it.

Last edited by UncleFred; 07-16-2010 at 01:44 PM..
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  #17  
Old 07-16-2010, 02:00 PM
Arnold Winkelried Arnold Winkelried is offline
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Thanks everybody for the comments!

t-bonham@scc.net: "Teaching science at a church Sunday school? Seems counterproductive." Really? Why? For further information, this is a Unitarian Universalist church.

All those who have warned me about the dangers of the glowing pickle experiment: I will discuss this with the other people in charge of Sunday School classes and see if maybe we should cut out that part. But I've already announced it as the highlight of the class!

Joe Frickin Friday : thank you for the simple way to do the glowing pickle experiment.

robby: Thanks so much for the link to Bill Beaty's articles! I will definitely use some of his explanations. I had forgotten all about his site!

Francis Vaughan : I like the idea of the motor, but I'm not very crafty. Do you have a link somewhere with simple instructions?

iamthewalrus(:3= : Same question as I asked Francis Vaughan. I'm afraid that building this breadboard would be beyond me.

UncleFred: you're right, it's here:
I can't plug in these new plugs! What's the deal?
You are an evil man. I will not have the children shake hands with Jesus.

Last edited by Arnold Winkelried; 07-16-2010 at 02:01 PM..
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  #18  
Old 07-16-2010, 11:56 PM
dracoi dracoi is offline
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I have used the water analogy with kids in the 8-12 range with success. It goes basically like this:

Electricity is a flow of electrons through a wire (conductive medium), like a sprinkler uses a flow of water through a hose.

Increasing the pressure of water is like increasing the voltage of electricity.

Increasing the volume of water moving through the hose is like increasing the amperage.

Some things conduct electricity very well; these are like hoses or pipes that carry water very quickly. Other things conduct electricity poorly or not at all. These are like rapids (lots of resistance, but some flow is still possible) or like dams (movement of the water is virtually impossible unless there's enough of it to break through).

Work is done by electricity as it moves just like water can turn a water wheel. Sometimes the water wheels just spin around randomly which in electricity is like a heater or lightbulb. Other times, they "turn together" which is like an electric motor that moves in a coordinated fashion.

If you think of the top of a battery as water at a high place and the bottom of a battery as water at a low place, you can see how the battery is used up. Water from the top moves down (doing work on those little water wheels) until it comes back to the battery at the bottom. If you want the water to do more work, you've got to get it back to the top, which is the equivalent of recharging a battery. In a non-battery situation, the electricity goes out, does work and comes back to a power plant. In water terms, the power plant lifts the water back up to the top so that it can run through the course again.

I generally haven't had the luxury of visual aids, but I've always liked the idea of a getting a trough of water that would take it from the top, circle around and return it to a cup at the bottom, turning a wheel as it goes. Then, on the other side, a battery with a loop of wire in the same pattern, turning a wheel with a motor.
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  #19  
Old 07-17-2010, 08:39 AM
Crafter_Man Crafter_Man is offline
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When it comes to educating students about electricity, I can't think of a better source than Bill Beaty's site:

http://amasci.com/ele-edu.html

I teach Physical Science 101 at a local university, and I use Bill's articles when teaching the electrical theory section of the course. They're spot-on.
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  #20  
Old 07-17-2010, 08:41 AM
Crafter_Man Crafter_Man is offline
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Quote:
Originally Posted by robby View Post
Back when I was teaching introductory physics, one of the best resources I ever came across for simple explanations of electricity were the articles written by the SDMB's own Bill Beaty. I would start here.
Dammit... should have read this thread more carefully.
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  #21  
Old 07-17-2010, 08:50 AM
Crafter_Man Crafter_Man is offline
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Originally Posted by dracoi View Post
Electricity is a flow of electrons through a wire (conductive medium)
To create electrical current, you must have charges that can move, a.k.a. "mobile charges."

Sometimes the charges are comprised of mobile electrons. An example is when there's current in a wire.

But current doesn't have to be made up of mobile electrons. When there is current through a battery, for example, the current does not consist of electrons - it consists of ions.

Same goes for electrical current through your body. The current consists of ions, not electrons.


As for the water analogy, it's O.K. But there are some problems with it:

1. Electrons do not "come out of the battery" on one side, and then "back into the battery" on the other side.

2. The energy is not due to the kinetic energy of the electrons moving in the wires. It is in the fields surrounding the wires.

Last edited by Crafter_Man; 07-17-2010 at 08:54 AM..
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  #22  
Old 07-18-2010, 09:47 AM
whitetho whitetho is online now
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Bzzzzzzzzzzzzz

Quote:
Originally Posted by UncleFred View Post
I believe The Master once described a little game for kids called "Shaking Hands With Jesus" (can't find the link) that would have taught the lesson.

But don't try it.
You would be thinking of Uncle Cecil's I can't plug in these new plugs! What's the deal?

Last edited by whitetho; 07-18-2010 at 09:47 AM.. Reason: Zap!
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  #23  
Old 07-19-2010, 04:11 PM
dracoi dracoi is offline
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Quote:
Originally Posted by Crafter_Man View Post
As for the water analogy, it's O.K. But there are some problems with it:
No disagreement with any of your comments. It's only an analogy and it can't be taken too far. It's lousy for explaining static electricity too. But, for a no-math, high-concept overview for young kids, I think it's a pretty solid start. Also keep in mind that I presented just a brief outline of what I'd normally spend half an hour explaining.
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