Lesson One: Craft a Simple Circuit

Learn how a simple circuit works so you can create your first circuit and light your first LED! You will learn how to craft a simple circuit, learn how Makey Makey works by completing a circuit, and learn how humans can connect to make a key press on your computer!

A Simple Circuit


Makey Makey works by completing a circuit. So it is important you build one to understand how a circuit works!

This activity is pretty straight forward, but it does require a few things that you may not have just laying around at home or on your desk at school. Here are the required tools and materials you need to be able to make this all work.


  • Scissors - Used for cutting paper, tape and other things other than your fingers!
  • Computer with Printer - To print a template for you to work with!


  • Simple Circuit Template- Template for creating a paper circuit!
  • Conductive Fabric Tape- Fabric tape that conducts electricty
  • Coin Cell Battery (CR2032) - Battery used to power our circuit
  • 5mm Red LED- The LED that we will light up!
  • Scotch Tape (Optional)- Used to tape down the LED!

Need Supplies? No LED? Hack a Tea Light!

Maybe you want to draw on cardboard instead, or use this idea with paints? All awesome ideas and we totally want you to play with the materials you have on hand.

Maybe you don't have access to an LED and/or a coin cell battery? Well, you might have these exact items in something at home in the form of one of those cheap LED tealights you can find at the grocery or home goods store! Usually you can find one laying and not being used. Ripe to be taken apart are repurposed!

Do you have anything small that lights up? You might have one of these dollar store tea lights you can use to craft a simple circuit. Here is a quick walk through in hacking a tea light to make a paper circuit. (Video includes how to draw out your circuit if you don't have access to a printer.)

The MOST Simple Circuit

First and foremost materials are conductive (conductor) or not (insulator). A conductor is a material that allows the flow of electrons through it easier. There is a range of how conductive something is, but that is for a different time! For now, just know that some materials can allow electricity to pass through it and others cannot.

A circuit is us creating paths or roads that are conductive that lead electricity along those roads to different locations and to do different tasks for us. The most simple circuit flows in a loop and can be done with just an LED and a battery as shown above. The current flows from the positive side of the battery, up through the LED lighting it up- and back down to the negative side of the battery completing the loop and closing the circuit.

To craft your circuit, you need conductive material to help the current and electrons flow so your LED will light up. When lighting an LED or a bulb it is also important to wire up your circuit with the correct polarity. If you hook up your LED incorrectly (say the positive side of the LED to the negative conductive trace) your LED will not light up.

If your LED doesn’t light up, no worries! You probably have it backwards. LEDs are special light bulbs that only let electrons flow through them in one direction, like a one way street! This is called polarity; something that will only work in one orientation. If the LED is backwards the electrons cannot pass through it, therefore not completing the circuit and not lighting up!

Checking an LEDs Polarity

There are a few ways that you can check an LED for its polarity. The easiest is to look at the length of its legs!

When you look at the two legs of an LED you will notice that one is longer than the other. They are supposed to be that way! The long leg is usually positive and the short leg is negative.

In technical terms the long leg (positive) is called the anode and the long leg (negative) is called the cathode. We try to keep things simple, but thought you may want to know! But, what if your LED legs are all bent up or trimmed down so that you cannot tell their length?

Not a problem, the bulb will tell you! Yep, that is correct the bulb itself has a marking (a flat spot on its rim) that is aligned with the negative leg of the LED. So, no matter how messed up the legs of your LED get, you can know which one is positive!

Need to cut to the chase? Here are 5 fun way to determine your LED polarity from maker Nikodem Bartnik!



Let's Craft a Circuit!

So, you have built the most simple circuit, but now it is time to take it to the next level and put some distance between the battery and the LED. by building a paper circuit. This quick activity will walk you through crafting your first circuit.

In the engineering world, we like to type "Hello World!!” as our first line of code. It’s a good way to imagine it is that you are taking the pulse of your project to make sure it is alive and well. With paper circuits, we say "Hello Light!" as that is the simplest thing that a paper circuit does… light up a light! We will first need to print out a template on a piece of paper. 

Download the template and follow along. 

Troubleshooting Tips

It is important to note that electrons are lazy and if they find an easier way to close the loop, you will short your circuit and your LED won't light up! So this means if you are having trouble lighting an LED with this simple circuit template, you should check:

  • Does the positive circuit trace ever come in contact with the negative circuit trace? Make sure to leave a gap under your LED. (If your positive trace goes directly to your negative trace, then the electrons will not be forced THROUGH the LED. Think of this like cats and dogs fighting- you have to keep the two lines separated!)
  • Do the circuit traces accidentally touch where you've made your battery connections?
  • Is your LED wired correctly?

Using the Template


The template is going to act as our road map for building our first circuit. As long as we follow the map we will be successful! Here are the instructions, step-by-step for you!

  1. Place the conductive fabric tape on the template where it is marked in the wide orange lines. (If you don't have conductive tape, you can use foil and a gluestick.)

You can use your scissors to cut the tape to length or if you are using copper tape, tear it.
2. Bend the legs of your LED and place the longer leg (the positive leg) on the positive copper tape trace.  Place the shorter leg on the negative tape trace. 
Pro TipYou may also want to put a few bends in each leg to give it more surface area and stability to keep it from moving around.
3. Use regular tape or more copper tape to hold the legs to the traces.  Make sure that the positive trace and the negative trace never touch.
4. Place the battery positive side down (Note that the coin cell battery has a plus(+) on its positive side) on the template and fold the paper as indicated so the electrons can flow in a loop!
If you were successful in building your circuit correctly your LED should light up when you fold the corner of the template up and around the battery and press it down!
Yes! Win! You have successfully constructed your first circuit. You now have “the circuit” in your tool belt for the future. Your understanding of a circuit is foundational in your use and success with Makey Makey, so be sure that you get everything working here. If for some reason your LED did not light up, check out the Troubleshooting section below to see what’s up.



A Makey Makey Circuit

The great news is that when you Makey Makey a circuit, you don't have to worry about polarity and you only have to have two conductive items and something that bridges that circuit to make the circuit a closed path! For example: One person can hold an EARTH wire and another person can hold a KEY PRESS wire and when they fist bump, it will complete the circuit and activate the Makey Makey. Alternatively, if one person holds both wires, the loop will always be closed and the circuit always complete!

Head to the Next Lesson

Once you've crafted a circuit, it's time for Lesson Two: Hands on a Makey Makey.


Simple Circuit: A circuit is a closed loop that allows current to flow. In our simple circuit, the electrons flow from the battery, up through the LED, and back to the power source. A closed circuit requires a conductive path, a power source, and a non-conductive area. You can open and close a circuit, we will learn more about this in the next few lessons!

Short Circuit: Electrons are lazy! If they can skip ahead, they will! Your electrons will skip the LED if they can find a conductive path around it! When using Makey Makey, the most common short circuit is the wires connecting or alligator clip heads touching. 

Polarity: There are two types of poles in electricity. A positive (+ Cathode) and a negative (- Anode). Some electrical components have specific polarity requirements. For instance, an LED will only light up if you have wired the polarity correctly to your power source. Whereas, some motors do not require a specific current direction and they will power either way you hook them up. Instead, the way you hook it up will change the direction of the spinning motor! 

LED: An LED is a light emitting diode. That means it is a particular type of diode that converts electrical energy into LIGHT! You are surrounded by LEDs! Can you think of things in your house that have LEDs inside that create a light source?




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