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First Circuits

Light UpYour Identity

How does a light know when to turn on? It doesn’t. Electricity has to make a full trip from the battery, through the light and back again. First you’ll find out what electricity is and how it moves. Then you’ll fold a paper stand with your name on it, build that trip inside it with copper tape, and make it light up when you press it.

  • Grades1–3 (with adult supervision)
  • Time30–45 min
  • LevelBeginner
  • Standards4 aligned
Heads up: adult supervision required

A grown-up must supervise this activity from start to finish.

  • Choking hazard: small parts. The LED and the coin battery are small enough to swallow. Not for children under 3, and keep them away from younger brothers, sisters and pets.
  • Coin batteries can cause serious burns inside the body within hours if swallowed. If you think a child swallowed one, go to the emergency room right away. Don’t wait for signs. US Poison Control: 1-800-222-1222.
  • The grown-up holds the parts. Hand out the LED and battery only when they’re needed, and collect any extras when you’re done.
  • LED legs are sharp. Push them through the paper slowly, away from fingers.

Button battery safety from Poison Control

You will need

ItemNotes
Square piece of paperOrigami paper or any paper cut square, about 6 in (15 cm)
Copper tapeAbout 1/4 in (6 mm) wide. Aluminum foil strips work too
LEDAny color. Small part: a grown-up holds it until it's needed
CR2032 coin battery3 volts. A grown-up holds it until the battery step (see Heads up)
Clear tapeTo hold the battery in place
Pencil and markersFor your name, drawings and + / − labels

What is electricity?

Everything around you, your desk, your shoes, even you, is made of tiny pieces called atoms. They’re far too small to see. Atoms have even tinier parts called electrons.

In some materials, like copper, electrons can hop from atom to atom. When lots of electrons move along together in the same direction, that’s electricity.

Inside a copper wire: tiny electrons, drawn as blue dots, all move along togetherZoom in on a copper wireelectrons moving together = electricityelectron
Fig. 1 If you could zoom in on copper tape far enough, you’d see electrons drifting along it together. That flow is what lights up an LED.

Here’s the surprising part: electrons themselves move slowly, but the light still turns on right away. That’s because the wire is already full of electrons. Push on one end and the push travels down the whole line at once.

A tube full of marbles: push one marble in at one end and another pops out the other end right awaypush one inone pops outall at the same moment
Fig. 2 A tube full of marbles works the same way. Push one marble in and a different one pops out the other end right away, even though no marble raced the whole way through.

How electricity moves: the circuit

Electricity needs three things to do work for us:

  • A push. A battery pushes electrons. Inside it, chemicals keep the push going until they’re used up.
  • A path. Something electrons can travel through, like copper tape.
  • A loop. The path has to go all the way around and come back to the battery. This loop is called a circuit.

Put a light in the loop and the moving electricity makes it glow. Break the loop anywhere, even with a gap thinner than a hair, and everything stops at once. A switch is just a way to open and close that gap on purpose.

Two circuits side by side. Left: the switch is open, leaving a gap, so nothing flows and the LED is dark. Right: the switch is closed, electrons flow all the way around and the LED glows.LED+−Gap in the loop: no lightLED+−Closed loop: it glows
Fig. 3 Same parts, one difference. On the left the switch leaves a gap, so nothing flows. On the right the switch closes the loop, electricity flows all the way around, and the LED glows. Your paper stand works exactly like this.
How it works

Which way does it flow?

We usually draw electricity flowing out of the battery’s + side, around the loop, and back into the − side. Scientists picked that direction more than 250 years ago, before anyone knew electrons existed. Later they found out the electrons actually travel the other way, from − to +. Both pictures work, so we kept the old one!

Stay safe

A small coin battery gives a gentle push that’s safe to touch. Wall outlets are completely different. They push hard enough to badly hurt you. Never put anything into an outlet, and never take apart anything that plugs into the wall.

Conductors and insulators

Electricity moves easily through some materials and can’t get through others.

Conductors: electricity moves throughInsulators: electricity is blocked
Copper tapePaper
Aluminum foilPlastic
CoinsWood
Paper clipsRubber and erasers

Materials that let electricity through are conductors. Materials that block it are insulators. That’s why this project works: the copper tape carries the electricity, and the paper underneath keeps it from leaking away. It’s also why real wires are wrapped in plastic.

Steps

  1. Watch it and gather your parts

    Now you know how a circuit works, so let’s build one. Watch the whole build first, then follow the steps below at your own pace.

    Watch it first The whole build from start to finish.
    Copper tape, one LED, a coin cell battery and a square piece of paper
    Fig. 4 Everything you need. No copper tape? Strips of aluminum foil work too; hold them down with clear tape. (Foil is a conductor too!)

  2. Fold your stand

    Start with a square piece of paper, colored side down. Make each fold in order. The dotted line shows where to fold and the arrow shows which way. Press every fold flat with your fingernail: sharp creases make the stand sturdy.

    Five folding steps that turn a square of paper into a standing name tent
    Fig. 5 Five folds turn a flat square into a stand. If a step is confusing, pause the video at that fold and match your paper to it.

  3. Make it yours

    On the front of your stand, write your name big. On the other half, draw or write one or more things you like: robots, plants, games, animals, anything.

    A finished stand with the name Ady written many times on one side and drawings of robots, plants, electronics and cars on the other
    Fig. 6 This is your identity: who you are and what you love. In a few steps it lights up.

  4. Add the LED

    Look closely at your LED. One leg is longer: that’s the + leg. The shorter one is the − leg.

    Push both legs down through the top edge of your stand, right in the middle, so the bulb sits on top and the legs poke inside.

    An LED being pushed through the top edge of the folded stand
    Fig. 7 The light sits on top where everyone can see it. All the wiring hides inside.

  5. Tape down the legs

    Gently open the stand so you can see inside. The two LED legs poke through, one on each side of the middle fold.

    1. Bend each leg flat, away from the middle.
    2. Press a strip of copper tape over each leg so the leg is trapped between the tape and the paper.
    3. Leave a gap in the middle. The two strips must not touch.
    Copper tape strips pressed over each LED leg on either side of the center fold
    Fig. 8 Each leg gets its own strip of copper. The strips are the start of two separate paths, so they can’t touch.

  6. Run the copper paths

    Now stretch each strip into a path:

    • From one leg’s strip, run copper tape up to the top point of the paper.
    • From the other leg’s strip, run copper tape down the side to the bottom corner.

    At a turn, fold the tape instead of cutting it. One unbroken strip means one unbroken path.

    Copper tape paths: one running up to the top point, the other running down the side to the bottom
    Fig. 9 Two paths, one from each leg. They meet the battery from opposite sides later, so keep them apart.

  7. Add the battery and test it

    Grown-up step: hand over the battery now, and stay close while it’s out.

    1. Set the coin battery at the end of the bottom path.
    2. Fold the top point down so its copper touches the top of the battery.
    3. Press. Does it light up? If not, flip the battery over and try again.

    Once it lights, check with your teacher or a grown-up, then label each path + or − with a pencil. The + path touches the side of the battery with the writing.

    The coin battery placed at the end of the bottom copper path, and labeling plus and minus with a pen
    Fig. 10 An LED only works one way around. Flipping the battery swaps which path is + and which is −.

  8. Lock in the battery

    Tape the battery in place so it can’t slide away, and make sure the copper on the folded top point lines up right over it.

    Taping the battery in place under the folded top point
    Fig. 11 The folded top point is your switch. When it presses the battery, the loop is closed. When it lifts, the loop is open.

  9. Fold it back and light it up

    Fold your stand back into shape. Push the bottom point up into the stand: the copper presses the battery and your LED lights up!

    It glows! Let go and it turns off. To keep it on, slide a pencil underneath so it keeps pressing.

    Grown-ups: the battery stays inside the stand, so keep it on a shelf or desk, out of reach of little kids and pets. When the battery runs out, cover it with tape and recycle it.

    The finished stand glowing blue on top, with a pencil holding the switch closed
    Fig. 12 Your name, your favorite things, and a light you wired yourself.

What just happened?

You built the same loop as Fig. 3, just folded up inside paper. The battery pushes electricity up one copper path, through the LED, and down the other path back to the battery. The folded corner is your switch: pressing it closes the last gap, and the LED glows.

The circuit as a loop: battery plus side, through the folded corner, along the copper to the LED, through the LED, along the other copper path, back to the battery minus sideLED+batteryfolded corner = switchcoppercopper
Fig. 13 Inside your stand, the copper paths, the LED and the battery make one big loop. Pressing the bottom closes the last gap, and electricity flows all the way around.
How it works

Why does the LED care which way it goes?

LED stands for light-emitting diode. A diode is a one-way door for electricity. Put it in backwards and the door stays shut, so no light. That’s why flipping the battery can fix it.

Why no resistor?

In later lessons, like Hello, Pico, you’ll add a part called a resistor to protect the LED. A small coin battery can only push out a little current, so it can’t overpower the LED on its own. Bigger batteries can, so don’t swap in a bigger one.

The story behind it

A battery made of coins

In 1800, the Italian scientist Alessandro Volta stacked discs of zinc and copper with pieces of cardboard soaked in salt water between them. The stack made a steady flow of electricity, and it was the first battery. The volt, the unit printed on your coin battery, is named after him.

Make it your own

Now you know the rule every circuit follows: two paths, one push, one complete loop. The stand is just one way to fold it. Real engineers take an idea that works and remix it, so try your own:

  • Fold a different shape. A star, a cat face, a paper cup, a fortune teller. Wherever the paper folds over onto itself, you can make a switch.
  • Move the light. Make it a lighthouse beam, a robot’s eye or a star in the sky.
  • Add a second LED. Give it its own two legs on the same two paths: long leg on +, short leg on −. Do both glow?
  • Go flat. Skip the folding and draw a circuit on a greeting card, with a corner that folds over the battery.
Design it like an engineer
  1. Sketch your idea first, and draw the two paths in pencil.
  2. Check that the paths never touch, except through the LED and the battery.
  3. Find your switch: which fold will press the battery?
  4. Test with the battery before you tape everything down. If it doesn’t light, flip the battery or look for gaps.
  5. Compare: build two versions. Which one is easier to press, or brighter, or sturdier?

More to explore: make a gap in one path and bridge it with foil, a paper clip, a coin, a straw or a leaf. Which ones are conductors? Or blink your initials in Morse code to a friend with your switch.

Stuck? Check these

  • Battery is upside down. Flip it over. This fixes it most of the time.
  • A leg isn’t touching. Press the copper tape down hard over each LED leg, or add another small piece on top.
  • The top point misses the battery. Line up its copper right over the battery, and press harder.
  • A break in the tape. Look for tears or cut corners. Patch them with a short strip of copper pressed hard over the gap.
  • The paths touch. If the two paths meet anywhere besides the LED and the battery, the electricity takes that shortcut instead. Separate them.
  • Dead battery. Try a fresh one.

What you learned

  • Electricity is tiny electrons moving together through a material
  • It only flows around a complete loop called a circuit: a push, a path and a way back
  • Conductors like copper let electricity through; insulators like paper and plastic block it
  • A switch opens and closes the loop on purpose
  • An LED is a one-way part, so the battery has to face the right way

Learn more

Standards

This lesson supports these standards from the Massachusetts Digital Literacy and Computer Science Framework and related frameworks.

  • MA STE 1-PS4-4Use tools and materials to design and build a device that uses light or sound to send a signal over a distance.
  • MA STE 2-PS1-2Test different materials and analyze the data obtained to determine which materials have the properties that are best suited for an intended purpose.
  • MA STE 3.3-5-ETS1-2Generate several possible solutions to a given design problem. Compare each solution based on how well each is likely to meet the criteria and constraints of the design problem.
  • MA STE 4-PS3-2Builds toward grade 4: Make observations to show that energy can be transferred from place to place by sound, light, heat, and electric currents.

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