Inspector Detector


  • 1

    Here are some of the materials you can use

    • binder clips
    • cardboard or a small box
    • newspaper (full sheets)
    • 1 paper cup (6-oz. or 8-oz [170-ml or 227-ml]) 
    • ruler or yardstick
    • scissors 
    • 1 sheet copier paper 
    • 1 small magnet for testing 
    • #3 steel wool pad 
    • string (about 20 in. [50 cm]) 
    • 5–10 strong magnets
    • tape (clear or masking)
  • 2

    Prepare ahead of time 

    • Have paper and a pencil ready to write down ideas and sketches as you design.
    • Make a pile of metal shards, or small pieces, of steel wool. Use a pair of old scissors and cut the steel wool into tiny pieces, about ¼ inch long. The metal shards can be sharp, so you may want to ask an adult to help with this step.
    • Make a grid map on a full sheet of newspaper. Draw a 10 x 10 inch (25 x 25 cm) grid on the paper. Label the sides 1–10 and the top A–J.
    • Think about how scientists might find magnetic fields on Mars, the moon, or other plants.
  • 3

    Think about the challenge

    • You will be searching for a magnetic field with your device. This is an invisible area of magnetism that is all around a magnet. How can you search for an invisible force?
    • What are some devices that deal with invisible energy? (Cell phones, compass, GPS, radios)
    • Think about why scientists might be interested in learning about magnetic fields on Mars, the moon, or other plants.
    • TIP: Planets, such as Earth, and moons with large amounts of fluids moving around can produce a magnetic field. Scientists can tell a lot about how the planet or moon formed and how it has changed by studying this magnetic field.
    • TIP: Magnetic fields draw away the damaging radiation of the sun and cosmic rays. This may be important for protecting astronauts.
  • 4

    Think about and write down ideas

    • How will you build a metal detector to help you find the hidden magnets? 
    • How will you be able to see when the metal shards move over a magnetic field?
    • How can you identify and record where the magnetic fields are located?
    • TIP: Inventors’ and engineers’ first ideas rarely solve a problem. They brainstorm, try different ideas, learn from mistakes, and try again. If things don’t work out, it’s an opportunity—not a mistake! This is part of the design process.
  • 5

    Look at the materials

    • What will you use to make a planetscape? (This is a simple model that looks like a planet’s surface. It’s where you will place your magnets.)
    • What materials will you use to make a device that will hold metal shards that will detect the magnetic field? 
    • Will the metal shards go in or on your detector?
    • How will you keep the metal shards from falling off your detector as you move?
  • 6

    Design and build the planetscape

    • Decide how you can build a planetscape that holds the hidden magnets. 
    • Your planetscape should be the same size as your grid map.
    • Choose materials that can allow you to have a large surface.
  • 7

    Design and build the planetscape (continued)

    • Plan where on your planetscape you want the magnetics to be placed.
    • Attach the magnets.
  • 8

    Hide the magnets

    • Place the grid map over the planetscape to hide the magnets.
    • Secure the grid map with tape so it doesn’t move around.
    • TIP: Use the grid map to record the location of each magnetic field by following the lines of the number on the side and the letter on the top. The spot that they meet at is the code you use to record the location, for example, 3-H.
  • 9

    Design and build the detector

    • Decide how you will build a detector that moves around the surface.
    • Think about how to keep the metal shards from falling off or out of the detector.
    • Choose the materials and build the detector.
    • TIP: Metal shards are very difficult to clean off a magnet, so keep them in an area away from magnets until you place them on or in the detector.
    • TIP: The metal shards will move around as they come close to a magnetic field, so make your detector large enough so the shards have room to move around or design a feature to keep them from falling.
  • 10

    Design and build the detector (continued)

    • Decide whether or not your detector needs a handle to help you move it around. 
    • Choose the materials and build the handle.
    • Place a small magnet on your detector. Test it before adding the metal shards.
    • TIP: Test your detector with a small magnet to see if you need to modify your design before adding the metal shards.
    • TIP: If the detector tips or bends, try adding another part to the handle to balance the weight of the detector. Or secure the handle with more tape.
  • 11

    Search for magnetic fields

    • Sprinkle the metal shards on or in your detector.
    • Move your detector slowly across your planetscape.
    • TIP: If you spill the metal shards, place magnets inside a plastic bag and swish the bag over the spilled shards. The shards will be on the outside of the bag. Lift the magnets out of the bag and let the shards will fall onto a sheet of paper. You might want to ask an adult to help you with the metal shards cleanup.
    • TIP: If your detector doesn’t respond, try holding it closer to the surface or check that you have enough metal shards. Also, check that nothing blocks how the shards move.
    • TIP: If the shards get caught under the detector or fall off the detector, try covering openings with tape.
  • 12

    Search for magnetic fields (continued)

    • Watch carefully and notice when the shards start to move around.
    • Move the detector slowly until you are right above a magnetic field.
    • TIP: If it is hard to see the shards move, try designing a window or removing parts that block your view.
  • 13

    Record your findings

    • Stop when you get over a magnetic field.
    • Record the location on your grid map.
    • Continue your search!
    • TIP: If you want to use your grid map at another time, use sticky notes to record the location codes. You can take them off and use your grid map another time.
    • TIP: When you are right over a magnetic field, the shards should be attracted and form one pile—that’s the point to mark on your grid map.
  • 14

    Did you know?

    • NASA Explores Space
      NASA’s Mars Global Surveyor spacecraft carries instruments that are used for measuring magnetic forces on the ends of its solar panels. These instruments are called magnetometers. The space mission used these instruments to determine that Mars no longer has a strong magnetic field—that means that the interior of planet has cooled.

      NASA’s Lunar Prospector spacecraft measured the strength of the moon’s magnetic fields. This space mission also used magnetometers to find the location of minerals and to determine the size and makeup of the moon’s core.
  • 15

    Try this next!

    • Go on a magnetic treasure hunt. Houses and schools are loaded with magnets. Use the detector to see how many invisible magnetic fields you can find. Check things like door closers, speakers, electric motors, and microphones.