Giant Magnetoresistance Activity

Students dissect a hard drive to explore the fundamental principles of electricity, magnetism, and a nanotechnology-based phenomenon called giant magnetoresistance (GMR). GMR is exhibited by materials that have alternating layers of magnetic and non-magnetic materials, each a few atoms thick. The resistance of these materials changes dramatically when a magnetic field is introduced. GMR materials can be found in the read heads of computer hard drives. Students participate in a scavenger hunt to find different components of the hard drive in order to win a prize. Students explore magnetism and electricity through hands-on demonstrations and must answer questions about these topics in order to receive visual clues to aid in their hard drive scavenger hunt. 

Full Instructions

Overhead Transparencies


  • Hard drives
  • Screwdrivers (Philips and Torx)
  • Poster paper
  • Tape Markers
  • Simple circuit demo (metal scraps, pieces of other materials, batteries, battery snaps, wire, LEDs)
  • Magnetism demo (cow magnets, metal scraps, pieces of other materials)
  • Coil LED demo (cow magnets, tube (rolled-up transparency) with copper coil attached to LED)
  • Worksheets