Educator How-To: Make a compass with a fish. A fish? Yes, a fish.


May 18, 2012
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Two thousand years ago, the compass — as we know it — was in its infancy. The Chinese made primitive compasses by carving a piece of lodestone (a naturally occurring magnetic iron-ore) into the shape of a ladle to represent the Great Bear constellation (we know this portion as the Big Dipper).  The finished ladle was then placed on a highly polished surface, where the larger end, or bowl, was attracted to magnetic north — causing the handle to point south.

The compass was eventually introduced to the west from China via Arab traders.  The Chinese possessed this important technology for more than a thousand years before the Europeans learned of it.

compass-01

During the Middle Ages, the Chinese set up several factories to produce compasses. One of the compasses produced was in the shape of a fish cut from a very thin leaf of iron — so thin that it could float on water by taking advantage of surface tension. The fish was then stroked against a lodestone until it was magnetized. When placed in the water, it would turn until its head pointed south and its tail pointed north.

Try your hand at making this south-pointing fish:

Materials:

Fish template
Pen (black Sharpie works well)
Permanent markers in bright colors
Scissors
Strong magnets
Large gauge metal yarn needle
Styrofoam meat tray (or any other flat piece of Styrofoam)
Large bowl
Water

Procedure:

  1. Tell the class the story about the Chinese being among the first to have compass technology.
  2. Explain that, in medieval China, a device known as the “south-pointing” fish was invented.
  3. Now tell students to get ready to make their own “south-pointing” fish!
  4. Using the template below, trace a fish onto a piece of Styrofoam and then cut it out.
  5. Use permanent markers to decorate your fish.
  6. Fill a large bowl with water.
  7. Place your fish into the water.
  8. Magnetize your needle by pulling it straight across the magnet several times or more, depending on the strength of your magnet.
  9. Figure out which way to place your needle on top of the fish so the fish’s head will point south.

fish

Congratulations! You’ve made a Nemo that can find its own way.

Kat
Authored By Kat Havens

Kat has been both the spokesperson for the CSI: The Experience exhibit and project manager for the Imperial Rome exhibit and has a love of all things historical and cultural. She is responsible for the Xplorations summer camp program, coordinating weekday labs during the school year, writing department curriculum and presenting at teacher trainings. Kat has worked at the Museum since 1996.

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