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Hack a Greeting Card

musical card

Activity courtesy of PBS Kids’ Design Squad Nation. View episode on YouTube [2:25]


In this activity, upper elementary students working alone or in pairs learn about electrical circuits and the design process by dismantling a “singing” greeting card and using the parts to build an alarm system.

Grade level: 3-6

Time: 50 minutes

Engineering connection

A circuit is the path along which electricity travels. When all parts of the circuit are connected, electricity flows. A break anywhere in the circuit stops electricity flowing. In one position, the switch breaks the circuit. When that happens, the electricity stops flowing, and there’s no music. In the other position, the switch completes the circuit. When that happens, the electricity flows, and music blasts!

Learning Objectives

After this activity, students should be able to:
  • Define, recognize, build, and draw a closed circuit.
  • Explain why a closed circuit is required for any electrical device to operate.


Next Generation Science Standards

Energy: Apply scientific ideas to design, test, and refine a device that converts energy from one form to another. [Grade 4]

International Technology and Engineering Educators Association

D. Tools, machines, products, and systems use energy in order to do work. [Grades 3 – 5]



  • Musical greeting card. (Before buying a card, ask around to see if someone has one to give you.)
  • Scissors
  • Tape
  • String
  • Hiding place


Click HERE for PDF in Spanish, and HERE for English.

  1. Find the electronics: Remove the part of the card covering the electronics.
  2. Cut open the inside cover of the greeting card to expose the circuitry.
  3. Cut out the electronics
  • Draw a line around the electronics. Include the tab on the other side of the card. This tab controls the switch that turns the song on and off.
  • Cut the line.
  • Make the song start and stop by moving the tab back and forth. This opens and closes the circuit.
  • Look closely to figure out how the switch works. Find the battery and the speaker.

4.   Add a pull-string

  • Tape a string to the tab.
  • Test the string by pulling it to open the switch.
  • Did the music start? If not, check that nothing is blocking the switch.

5.  Tape your card in a secret place

  • Try something with a lid, like a lunchbox, box, or cookie jar. Or find something that opens, like a locker, cabinet, or refrigerator door.
  • Tape the card in place.

6 Tape the string so that when the jar or door opens, it gets pulled. This will open the switch.

7. Set the trap.

8. Gotcha!

Activity Extensions

  • Booby-trap other things. Lockers, books, refrigerator, drawer, medicine cabinet, toilet handle, etc.
  • Wear it. Mount your hacked greeting card to a band that you can wear on your arm or leg or under your hat. Attach a long string to the switch. Secure the card to your arm, leg, etc. Then put on something that fits loosely, like sweat pants or a sweatshirt. Run the string through the garment so you can grab the end. When you want the music to blast, pull the string to open the switch. SURPRISE!

Additional Resources


Completing the Circuit [Grades 3 – 5] Students build basic circuit from wire, lightbulb, and power source. [From] 

Switcheroo [Grades 3-5]  Students construct a simple switch and determine what objects and what types of materials can be used to close a switch in a circuit and light a light bulb. [From]


How wiring batteries in a series works PBS Kids’ Design Squad Nation. [0.25]


How to Hack an Audio Greeting Card Circuit bending, the art of modifying existing electronics such as children’s toys or inexpensive, battery-powered musical instruments to create unique musical or video instruments, requires no prior knowledge of electronics. There’s even a video art, called glitch, made from hacking battery-powered video devices.

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