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Triangulation, a Scientist
and a Seal
Grade: 4th - 6th grade
Goal: This activity
will demonstrate in layman's terms how triangulation can
be used to locate an individual animal.
Objective: Students
will be able to demonstrate the basics of triangulation
and how it is used to locate animals, people, etc.
Materials: Clear a large
open space in the classroom or take students to the gym
or outside.
· Charts of Alaska
· Pencil
· Paper
Activity:
Explain to the students that they need to locate a seal
that has been reported in Prince William Sound. A researcher
from the Alaska SeaLife Center (ASLC) needs to take photographs
of this seal for the National Marine Fisheries Service
(NMFS). They are interested in recording data on seals
once they have been released from the ASLC Rehabilitation
program. The ALSC researcher is communicating with assistants
in the field. A fisherman has reported seeing a seal with
a flipper tag from the Center. Ask a student to be the
seal.
Choose another student to be
the first point of reference, a mountain. The "mountain"
should be about 10 feet from the "seal." Lets
assume that the fisherman sighted the seal close to the
coastline near a mountain.
(The "assistants"
may find it easier to put a symbol for the mountain on
a piece of paper and discuss where the seal might be in
relation to the mountain.)
· Will this information
help the assistants? How certain of the seal's location
can they be?
Choose another student to represent
the second point of reference: a salmon hatchery. Position
the hatchery about 8 feet away from the seal, so that
the seal, hatchery, and mountain form a triangle.
The researcher now has two
points of reference for the assistants in the field. (e.g.
you should see a fish hatchery to the North and a mountain
to the South.)
· Are the research assistants
able to narrow down the seal's location better?
Choose one more student to
represent the third point of reference: a large navigational
aid, like a buoy. (The navigational aid should be about
6 feet from the "seal.") Now the mountain, hatchery,
and navigational aid form a triangle around the seal.
Now have the researcher ask
the assistants in the field to locate all three references.
("I can see the mountain to the South, the fish hatchery
to the North, and the navigational aid to the East.")
Using 3 points, the research assistants can now triangulate
the position of the lost seal.
This is how Global Positioning
Systems work (GPS). Instead of mountains, fish hatcheries
and other points of reference, GPS uses highly accurate
satellites as points of reference. Satellite tags communicate
with orbiting satellites, getting signals from at least
three of them to "triangulate." This enables
the receiver to display an animal's position to within
100 meters.
