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Materials and tools

Khan Academy video wrapper


  • 7 alligator clips (e.g., RadioShack #270-380 mini alligator clips)
  • insulated copper wire, 22- or 20-gauge solid copper, 5 ft (1.5m)
  • wooden board for base, approximately 3.5 in x 8 in (9 cm x 20 cm), can be made from 3/4-in standard shelving or plywood
  • 470-ohm resistor (RadioShack #271-1317)
  • 2 paper clips
  • 9-volt battery
  • Velcro with adhesive back, approximately 1 in x 1 in (2.5 cm x 2.5 cm), to hold the battery to the board
  • 9-volt battery snap connector (e.g., RadioShack #270-325 or #270-324)
  • 6 sheet-metal screws, #8 x 5/8 in
  • 6 small flat steel washers (SAE #10)
  • light-emitting diode (LED) (e.g., RadioShack #276-066 High Brightness Red LED)
  • 2 phone plugs, 1/8 in (e.g., RadioShack #274-286 or #274-287, sometimes called mini plug; make sure you get a monoaural, not stereo, plug)
  • amplified speaker (e.g., RadioShack #277-1008)
  • solar cell (e.g., Edmund Scientific Co., 800-728-6999, www.edsci.com, #30398-09)
  • small radio with headphone jack (e.g., RadioShack #12-799)
Note: Two premade 6-ft. audio cables with a 1/8-in phone plug on one end and two alligator clips on the other end (e.g., RadioShack #42-2421) can be substituted for the two phone plugs, about 3 ft (1 m) of the wire, and four of the alligator clips in the list of materials above. One of the cables will have to be altered slightly so that its alligator clips are far enough apart to be connected to the paper clips at screws 1 and 4.
Khan Academy video wrapper


  • needle-nose pliers
  • wire stripper
  • small drill
  • phillips head screwdriver

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