Science at Home

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Holiday City Circuit

Holiday lights glow because of electricity. Build a simple electric circuit from aluminum foil and a string of holiday lights to learn about what conducts electricity and what doesn't.


  • Aluminum foil
  • Single LED light, or one from a string of holiday lights (note: the string of lights may no longer work when you disconnect one light)
  • Wire strippers (if using a string of holiday lights)
  • Glue stick
  • Clear tape
  • Holiday City Circuit template (PDF)
  • Paper
  • 3V button battery
  • Scissors
  • Items to test for conductivity, like buttons, paper clips or toothpicks


  1. Download and print out the Holiday City Circuit template.
  2. Cut several strips of aluminum foil that are about 1/4-inch wide. They do not have to be exactly measured. The strips of foil should be a little bit longer than each of the segments of the square circuit template.
  3. Glue the foil down on each segment to create a circuit. Rub the glue stick thoroughly on one side of a piece of foil, making sure to go all the way to the ends. Carefully glue it in place, making sure there are no gaps between pieces of foil -- the foil pieces should make a complete square.
  4. If you're using a light from a string of holiday lights, cut it off the string along with a couple inches of wire on either side. Use the wire strippers to expose the copper wire at the ends.
  5. If you're using a single LED light, gently bend the wires so they stick out sideways from the bulb.
  6. Use clear tape to connect the wires to the aluminum foil in the spot indicated on the template. Make sure the metal is touching the foil and is securely held down with tape.
  7. Place the battery in the circle and fold the corner over so the other circle lines up with the top of the battery. The foil should be in direct contact with both sides of the battery. If all of the connections are good, the build should light up!
  8. Test different objects to see if they conduct electricity. Cut the circuit as indicated on the template. Place the items that you're testing on both sides of the cut circuit. The light will turn on if the object conducts electricity.

What's happening?

An electric circuit can be as simple as a flashlight or as complicated as a city power grid. A simple circuit contains a power source (battery), wires, switch and a load (light bulb). The word "circuit" sounds like "circle," and a circuit needs to be circular, or connected, to work. If there is a gap or break in the path, the circuit isn't complete and the light won't turn on.

A complicated city power grid uses an electrical generator to produce very strong electrical currents. The electricity travels along metal wires to where it needs to go. On its way, it needs to be stepped down, or weakened, before it can safely power your electronics. The wires connect the power source to the devices and back again. Think of your phone or microwave as the light in the circuit that you just made. This creates the path for electricity to travel. 


If the circuit isn't lighting the bulb, make sure all the pieces of aluminum foil are overlapping so they are well connected. LED bulbs only work in one direction. If your bulb is connected but not working, try flipping the battery to make the electricity flow in the other direction.  

Recommended reading

How Does My Home Work? by Chris Butterworth

Blackout by John Rocco