How I Teach Electricity: Ideas, Activities & Resources
Here’s how I teach electricity and the specific tools and activities I like to use.
My Overall Approach:
Keep Concepts as Grounded-in Reality as Possible
Electricity is super hard to teach because it’s full of abstract concepts built on abstract concepts. And all tiny and invisible and hard to imagine.
So, today, I wanted to give you my favorite resources for teaching electricity that I’ve found/made over the years, plus my thoughts on best practices for teaching it to kids.
These are the ways I’ve found that have worked the best for me in my teaching, and they’re also based on the research I did with the Physics Education Group at the University of Washington.
I’d love to hear what’s worked well for you, too!
A lot of this is pretty standard. I use a pretty common order for how I bring up topics, and I do use a bit of the very common ‘water in pipes’ metaphor to explain things. But I do some things a bit different, too, and my primary goal is to give a student an understanding of electricity that’s grounded in their own everyday experience, and some mental models that will provide useful intuitions as they reason about physics situations.
Start with Static Electricity
Start with static electricity and the idea that everything in the world is made of atoms, and that these atoms are made of little charges.
The central part of the atom (the nucleus) has positive charges (protons) and neutral charges (neutrons). And the large amount of empty space around each nucleus contains little teeny tiny negative charges (electrons).
Blow up a balloon, play around with it, rub it on a sweater, stick it to the wall, rub it on your head and watch what your hair does. Have students wonder about why that might be happening, and then take a look at these two Phet simulations to start to build a mental model of the atomic-scale world:
Phet Simulations for Understanding Charges
John Travoltage
I like this one, because it connects to an experience we’re all familiar with, and it shows what’s happening at an atomic level.
This is a super simple little simulation, but very helpful. Open the simulation, and drag his foot back and forth across the floor.
It shows the charges moving up his leg, and if you then move his hand to the door knob, you can see the charges flow out his arm, and the spark they create.
https://phet.colorado.edu/sims/html/john-travoltage/latest/john-travoltage_en.html
Static Balloon
I like this one next, because again it’s something we’re familiar with. Without using this kind of simulation, we run the risk of a student’s understanding of electricity just being this theoretical thing completely disconnected from their everyday experiences.
And we don’t want that! We want physics classes to improve our actual understanding of our everyday lives and the world around us!
So, my recommendation is to play around with some balloons, then play around with this simulation for just a couple of minutes.
Some Math You Could Introduce at This Point
At this stage, I think it’s useful to talk about how we measure amounts of charges in Coulombs. And that we can have positive or negative numbers, because we have positive or negative charges.
For older kids who have done scientific notation, it’s a good time to introduce that an electron has a charge of -1.6 x 10^-19 Coulombs, and that a proton is the same but positive.
I think it’s also good practice to convert between numbers of electrons and amount of charge at this point. (Like, if you have 5 Coulombs of charge, how many electrons do you have? And vice versa. I’d start with converting electrons to Coulombs because it’s easier because it’s just multiplication.)
If you have 6 electrons, then just multiply 6 by the charge of a single electron to get the total charge.
If you have -10 Coulombs of charge, divide 10 by the charge of an electron to get the number of electrons.
The scientific notation already makes it abstract and tough for kids, but it’s good to start getting more comfortable with scientific notation, if it’s not too hard/frustrating.
Next, Introduce the Idea of a Flow of Charges
You can already see this in the Travoltage simulation, which is great. Plus, it’s not too big of a conceptual leap to imagine charges flowing.
I like to introduce current before either voltage or resistance, because it’s easier to visualize.
Current is the flow of charge. It’s measured in Amperes (Amps). Technically, it’s the number of Coulombs of charge that flow past any point in a circuit every second. (1 Amp is 1 Coulomb per second).
I always imagine I’m sitting on a dock next to a river, watching the water flow past. Water current might be measured as the number of gallons of water that go by every second.
Electric current is the Coulombs of charge that go past every second.
The letter we use to represent current is ‘I’.
Then, Introduce Resistance
This one’s just one step up, and now that we’re imagining water flowing past a dock, it’s pretty easy to imagine resistance.
Resistance is how hard it is for the current to flow through a particular path.
Here I might talk about conductors and insulators. About how some materials hold their electrons really tightly, and some really loosely.
I usually use a neighborhood metaphor here. What was it like where you grew up? I remember when I was a kid, there were some neighborhoods where the kids were just running around all over the place. In and out of different houses. The kids are like electrons, and the houses are like the nuclei of atoms. Sure, each kid might belong to their own house, but they run all over the place. Those neighborhoods were like conductors. Electrons are able to flow freely.
In other neighborhoods, everybody stays in their own house. Kids stay inside, and don’t go out much. Or, it’s hard to get them to leave, anyway! Those neighborhoods are like insulators.
I also like to use a hallway metaphor, because we’re all familiar with hallways. ALSO we can use the hallway metaphor to address a very common misconception in electricity.
Have you ever had to get from one place to another in a building? Maybe you have to get from math class to Spanish class. And maybe there are a few different ways you could go. Maybe there’s a long, narrow hallway, and a short wide hallway. You’d probably take the short, wide hallway, because it’s easier.
Wires are like hallways that current can flow through.
EXCEPT you have to say that each hallway is already packed full of people, and all the people are moving along together.
Because one of the most common misconceptions most of us come into electricity with is that wires are like these tubes, and current gets poured out of batteries into these tubes. And that the current flows through the tubes and then gets ‘used up’.
It’s an understandable way to think about electricity, but it’s incorrect.
Because everything is made up of charges.
A wire is already FULL of charge. Batteries just push those charges along.
That’s why I like the Spintronics activity. Because it uses belts/chains to represent wires, you can see that electricity isn’t like a fluid flowing from one place to another, it’s actually a bunch of electrons all crammed together marching along as a group in a circuit.
Lastly, Introduce the Most Abstract Concept: Voltage
Okay, so I usually cheat slightly here.
Of course, the precise definition of voltage is that it’s the potential energy per charge.
I do always start by telling students that. And that we measure voltage in Volts, and that a Volt is literally a Joule per Coulomb, because Joules are energy. And that if you have a 9 volt battery (whenever possible, I use things that are real that students have encountered) it means that every Coulomb of charge has 9 Joules of energy.
I also do sometimes make the comparison to gravitational potential energy, and of water flowing downhill.
I know that voltage is not a force. I tell students that.
But, to be honest, thinking about Voltage as the thing pushing the charges through the wires actually generally leads to some correct intuitions.
So, this may be controversial, but I usually tell students that it’s okay to think of voltage as the thing pushing the charges through the wires, as long as they know that it’s actually the potential energy per charge.
Force is a helpful bridge to understanding the truth, because it makes Ohm’s law easier to get a feel for.
It’s also helpful to tell students that a AA battery has a voltage of around 1.6 volts. Again, it’s just helpful to make as many real-world connections as possible.
You could also Make a Lemon Battery at this point, which generally has a voltage of around 1 Volt.
Now We Can Do Circuit Problems!
Whew. Once we get through understanding charge, conductors and insulators, current, resistance, and voltage, we’re in the clear.
Now we can talk about circuits! I like to start by playing around with the DC Circuits Phet Simulation, just so they can get a handle on the idea that you have to connect both ends of the battery to a bulb in order for it to light, and that you have to make a complete circuit.
Then, we have some super awesome options for making circuits and playing with LEDs!
Circuit Activities
Squishy Circuits
I love this activity, because it again makes circuits into a real, everyday thing. You can actually make conductive and insulating salt dough at home, and then, with some simple LEDs, you can make cool, light-up sculptures!
Paper Circuits
And, lastly, I love this activity from the Exploratorium, because it dovetails so nicely with stories and fairy tales. You can create illustrations, and then use copper tape and LEDs to light them up!
https://www.exploratorium.edu/tinkering/projects/paper-circuits
Ohm’s Law
At that point, we can introduce Ohm’s Law. I prefer to teach students Ohm’s Law in the I=V/R format, because in this way, the form matches the causality. What I mean is, the combo of voltage and resistance is what causes whatever current you get.
More voltage means more current. More resistance means less current.
I know many teachers will teach all three forms and rearrangements, and I know that can help for some students who have trouble rearranging equations, but I think that method actually does students a disservice conceptually, and makes them have to memorize more. Plus, it makes it seem like there are three different cause and effect relationships, and just splits the idea into 3 pieces, conceptually.
Power
One last topic! When I’m teaching power, I always start with 60 watt light bulbs, horsepower, and food calories.
Energy is also one of those abstract concepts that’s tough to understand, so I always start by having students pick their favorite food, calculating the calories in some typical amount of that food, and then having them calculate how long that amount of food would power a 60-Watt light bulb if energy could be transferred to it perfectly without any loss (which, of course, it’s important to say it can’t!)
So, we talk about how capital C Calories, or Food Calories, are actually kilocalories, which was why I was briefly traumatized when I went to Italy, had some gelato, and then thought I’d somehow eaten 200,000 calories in one sitting.
1 Food Calorie = 1,000 calories (typical thermodynamics calories, where 1 calorie is the amount of energy required to raise 1 gram of water 1 degree celsius.)
And 1 calorie = 1.484 Joules of energy
1 Food Calorie = 1,484 Joules
I might have them lift something heavy a few times, calculate the energy they used (by multiplying the weight of the object in Newtons by the distance they lifted it) and dividing by the time it took them. That gives them their power in Watts!
When I talk about power in electric circuits, I again only use one form of the equation:
P = IV
I tell students they can remember it because it’s like an IV that goes in your arm. It powers you. (Okay, an IV doesn’t really ‘power’ you, but it makes it stick in kids’ minds. Research shows that giving students memory devices like this will drastically improve recall. They don’t even have to come up with it themselves. There’s definitely an art to creating ‘sticky’ memory devices, and that’s a useful skill to teach students, too, but I spend a lot of energy collecting effective memory devices. This one really works!)
List of Resources
I go into more about each of these in the ‘How I Teach’ sections, but here are the resources I like the most:
The Sorceress of Circuits Interactive Story Game: This is a story game I created. You’ll see below that there’s a specific order for the introduction of ideas I think works really well to help students build a solid conceptual understanding of circuits, and that’s what I used in this game. It teaches kids everything I talk about below, except power and Ohm’s Law, plus parallel and series circuits, all from the very basics so kids don’t need an pre-existing knowledge to play. I also structured the game so that it teaches a small piece of information and then gives immediate practice, so that students understand each piece of content before moving onto the next piece. It works well as a way to introduce a unit, or as a fun review activity.
John Travoltage Phet Simulation - a fun visualization that connects theory to real world experience
Static Balloon Phet Simulation - another fun visualization that connects theory to real world experience
Spintronics - A great hands-on game that corrects the most common misconception about current
Make a Lemon Battery - It’s great to use everyday objects wherever possible!
DC Circuits Phet Simulation - A quick way to practice the idea that you need to make a complete circuit in order for current to flow
Squishy Circuits - A really fun hands-on activity, and another way to make electricity real and tangible
Paper Circuits - Another way to make circuits tangible, plus it really lends itself to combining with art and stories