Energy systems


10. Design an ElectroFying ElectroCity


An ElectroFying ElectroCity is a mystery box or car that surprises you with sound, light and/or motion when you trip a hidden switch. Students use anything they have learned to create these culminating projects. Optional extensions provide some additional resources: how to understnad and use series and parallel circuits; and how to make magnetic proximity switches.

Advance Preparation

  • Post a sheet of chart paper labeled Ideas for ElectroFying ElectroCities
  • Photocopy worksheet and assessment (downloadable at bottom of page)
    NOTE: Additional preparation is needed for the two extensions; click on links at bottom of Procedure for details.


  • Same materials as for Lessons 6-9: Motors, AA batteries, bushings, wheels, LED’s (including IR and UV devices), buzzers, coin batteries, paper fasteners, paper clips, clothespins, aluminum foil, hook-up wire, strippers, cardstock, scissors, tape, boxes
  • Craft materials
  • Storage bags for holding work-in-progress NOTE: Additional materials are needed for Extension 2; click on link at bottom of Procedure for details.


  1. Brainstorming ideas: Review all the major circuits and devices developed so far. Students will now have an opportunity to use any of these to design and make their most surprising and complicated projects. These projects should use hidden switches and any of the other sources students have learned to use. Conduct a brainstorming session with the class to elicit ideas for ElectroFying ElectroCities. Chart all the ideas. For additional suggestions, see Troubleshooting.

  2. Designing the ElectroFying ElectroCity: Ask students to record their ideas in their Science Notebooks or on the Worksheet. They should include the basic idea, parts, location and method of operation of the hidden switch(es), a drawing of how it will look and a circuit diagram using standard symbols.

Extensions: The two optional extensions provide additional resources for designing and making ElectroFying ElectroCities. The first extension shows how to understand and use series and parallel circuits to overcome the problem of powering and controlling two different-color LED’s from the same battery and switch. The second extension develops electrical and magnetic properties of materials, and uses these insights in making a magnetic proximity switch, which can control a circuit from a distance.


Worksheet: Design an ElectroFying ElectroCity

Design an ElectroFying.docx


Here are some ideas students have had for ElectroCitiy:

  • Buzz Box, which buzzes and/or vibrates when you close it;
  • Light wheel: LED’s are taped to a wheel, which spins when you open the box;
  • Jitterbug: a vibrator mounted on a platform that is supported by thin wire legs, made from paper clips; when the vibrator is on it makes the platform move around randomly on a smooth surface;
  • Light-up: a pop-up card with a hidden switch that turns the lights on as the pop-up piece folds out; click here to see a unit on making pop-ups;
  • Guitar: A noisemaker that repeatedly hits a rubber band, stretched across a small box; tighten the rubber band by twisting it with a stick under the box to change the tone;
  • Kitchen: A set of toy appliances, such as a stove that glows red through a transparent window when the door is closed, a dryer that spins when the door is closed, and a refrigerator that blows air out and turns on a light when the door is opened;
  • Aquarium: a box with fish drawn on the inside that glow through a small window or peep hole when the box is closed; the UV LED inside could be controlled by an IR remote;
  • Kaleidoscope: LED’s mounted inside a cardboard tube, activated by a hidden switch or IR remote somewhere on the tube;
  • Disco: a rotating ball, covered with aluminum foil, illuminated by an LED.