Light Up Paper Circuits

A paper circuit is one of the simplest ways to introduce electronics. Using copper tape, a coin-cell battery, and an LED, students will build a complete electrical circuit on a piece of paper. Once the circuit is complete, the LED lights up without any programming or soldering.

The activity works well because students receive immediate feedback. If the LED lights, they know their circuit is complete. If it doesn’t, they can inspect each connection and figure out where electricity is no longer able to flow.

At the end of the activity, every student should leave with a personalized light-up card that they can take home.

Completed paper circuit using copper tape, a CR2032 battery, and two LEDs.

Materials

For each student

• One printed circuit template, perferrably on carstock
• 12 inches (30 cm) of copper tape
• One CR2032 coin-cell battery
• One LED
• Colored pencils or crayons

For the instructor

• Additional copper tape
• Extra LEDs
• Extra batteries
• Scissors
• Projector
• Printed example

Before You Begin

Print one circuit template for every student using cardstock rather than ordinary printer paper. Cardstock is much more durable and holds the copper tape flat while students work.

Cut the copper tape into approximately 12-inch strips before class begins. This saves a surprising amount of time once students are seated.

Open each package of batteries ahead of time. Coin-cell batteries can be difficult for younger students to remove from their packaging.

Lay out the LEDs in small containers so students can choose their favorite color as they arrive.

Before class begins, build one completed example yourself. Keep it nearby throughout the activity so students can compare their work if something isn’t functioning correctly.

Preparing all of the materials before students arrive allows the lesson to move at a steady pace.

Teaching the Lesson

Begin by asking a simple question:

“What does electricity need in order to make a light turn on?”

Allow students to offer a few ideas before introducing the concept of a circuit.

Explain that electricity can only flow when there is a complete path from one side of the battery to the other. If that path is broken anywhere, the light will not turn on.

Avoid using words like series circuit, voltage, or current. They are not necessary for this activity.

Instead, focus on one simple idea:

Electricity needs a complete loop.

Building the Circuit

Project the template on the screen and build the circuit one step at a time.

After demonstrating each step, stop and let students complete the same step before continuing.

This keeps the class together and gives volunteers time to help anyone who falls behind.

Have students:

1. Color their design before adding any electronics.
2. Place the copper tape along the printed circuit paths.
3. Fold the battery flap.
4. Insert the battery.
5. Place the LED through the paper.
6. Tape the battery closed.
7. Test the circuit.

Walk around the room while students work.

Instead of fixing problems yourself, ask questions.

• Does your copper tape touch all the way across?
• Is the battery facing the correct direction?
• Is the LED inserted the same way as the example?
• Is the tape firmly pressed onto the paper?

Students can choose their LED color while collecting materials before they begin building the circuit.

Understanding Why It Works

Every battery has two terminals.

One side pushes electricity out.

The other side allows electricity to return.

Copper tape acts like a wire by carrying electricity across the paper.

The LED only lights when electricity can travel in a complete loop from one side of the battery, through the LED, and back to the other side.

If any part of that loop is interrupted, the LED stays off.

A complete loop allows electricity to flow from the battery, through the LED, and back to the battery.

Troubleshooting

Most paper circuits fail for one of four reasons.

The LED does not light

Unlike a small incandescent bulb, an LED only works in one direction. First try flipping it around. If that doesn’t solve the problem, just get a new bulb and test it using one of the cr2032 batteries used for the circuts.

The copper tape is not making good contact

Copper tape conducts electricity much better on its top surface than through the adhesive.

Students often try to fix mistakes by overlapping many short pieces of tape. Those overlaps do not always make reliable electrical connections.

If the tape was applied incorrectly, remove the section and replace it with a new piece instead of trying to patch it.

The tape is torn

Inspect every corner where the tape bends.

A small tear is enough to break the circuit.

The battery moved

Check that the battery is still firmly pressed against both pieces of copper tape.

Most problems can be found by carefully tracing the electrical path from one side of the battery to the other.

Cleanup

• Remove unused batteries from the tables.
• Return unused LEDs to their container.
• Save remaining copper tape for future classes.
• Collect scissors and colored pencils.
• Allow students to take their completed paper circuits home.

Finished paper circuits ready to take home.