Rationale
Modelling the motion of the pack ice, students will learn about the
meteorological and oceanographic conditions in Antarctica and also see the
effect of topography on sea ice movement.
Grade Level/Discipline
Middle School
Objectives
Students will inquire into the factors that create sea ice movement, and will
create models of that movement.
National Standards
UCP 2,3; A1,2; B2,3; G 1,2,3.
Teacher Preparation for
Activity
Pre-activity set-up
Set up water tubs, procure and assemble other materials.
Materials
Several large plastic tubs; sheets of plastic or wood laminate about 10x10cm
which float, packing popcorn, simple anemometers, hair dryer to generate wind,
meter sticks, watches with second hands or stopwatches, detailed map(s)of
Antarctica, access to the Internet and a printer.
Time Frame
2-3 periods
Teaching Sequence
Engagement and Exploration (Student Inquiry Activity)
Ask the class:
How fast can the ice pack move? What are the factors that might control the
speed of the movement? What factors control the direction of the movement?
Read or recite the following story to the class:
In 1914, Sir Ernest Shackleton sailed to the Weddell Sea off Antarctica.
His plan was to traverse the continent. His group aboard his ship, the
Endurance, was to land at Vahsel Bay on the west side of the Weddell Sea and
then go to the South Pole. Then to get to McMurdo Sound, he would rely on
depoted food and supplies left by a second group which would land at
McMurdo. A fine plan- except he never got closer than 120 miles to Vahsel Bay.
(At this point study the map of Antarctica and point out the WeddellSea, Vahsel
Bay , the South Pole and McMurdo Sound.)
The Endurance was frozen into
the pack ice, and thus began one of the most incredible stories of leadership
and survival in human history. Unlike the poor unfortunates on the Jeannette,
most of whom perished when frozen in in 1880, Shackleton was, through
unbelievable trials, able to bring back his entire crew alive. (read Alfred
Lansing's Endurance.)
When Endurance was frozen in she began to drift with the pack. She
drifted north at first and then west towards the Antarctic Peninsula. (Map). Help
was available there at whaling stations and in depots known to exist on Paulet
Island. But then, after many months, Endurance was crushed in the grip of the
moving ice and sank. Shackleton and his men were forced onto the pack ice
itself. They tried several times to walk out by sledging their life boats behind
them, pulling the boats with ropes attached to harnesses they had fashioned for
themselves, manhauling. Due to the pressure ridges and the soft condition of
the ice in the Antarctic summer, they were able to make only about a mile a day.
They soon gave up, resigned to the fact that they would have to depend on the
movement of the ice pack itself to bear them close enough to help to make a
final dash for life. They settled in making camp to ride along on the pack ice.
As they sat in their camp, cold, exhausted, bored day after day, Shackleton kept
hoping for a storm from the south. Taking latitude and longitude readings every
day he found that the rate of drift was too slow . The Antarctic winter was
coming on. Wintering over was almost beyond question. Only a storm from the
south, from off of the ice-laden Antarctic continent ,could help them. They would
have to suffer tremendously low temperatures and high winds. Yet Shackleton
prayed for a storm. At last the storm came. His positon readings showed that in
six days they had travelled nearly eighty miles to the northnortheast. Paulet
Island was to the northwest but the storm had given him hope.
Ask the class: What factors make sea ice move?
Present them with the tubs and ice "floe" materials. Using meter sticks and stop
watches, have them measure the speed of their floes across the tub under the
influence of the hair dryer generated wind. have them fill out the following work
sheet:
Name __________________________ PD_________
Trial # / Floe material/ Wind speed (anemometer) / Floe speed/ Remarks
Have each group do at least ten trials. Suggest that they vary the floe
materials,wind speed, and angle and come to some conclusion about which
situation makes the floe move the fastest. Try adding islands to the tub and look
for refraction patterns using packing popcorn as one of your floe materials.
Explanation (Discussing)
Shackleton's floe moved at about twelve miles/day for that short time. The
winds were in the sixty miles/hour range. Have a class discussion or sharing of
their results. Compare their model wind speed and floe speed to Shackleton's
results.
Elaboration (Polar Applications)
Using the internet and maps monitor in real time the conditions -wind speed
and direction- in the Weddell Sea on a daily or weekly basis.
During the course of the Internet monitoring, ask "Now you are a modern
Shackleton. You are at 78S 50 E. Locate this posuition in the Weddell Sea.
Which way are you moving with today's wind speed and direction and how fast
stranded as you are on an ice floe? How long before you get close enough to
land to make a dash for it? Where will you land, what island will you try
for?etc" . This data can be gotten from the Glacier Weather sites
../weather/butlerisland.html and ../weather/larseniceshelf.html
There's both satelite imagery in real time and composite movies as well as
synoptic weather data (station models and the like).
Exchange (Students Draw Conclusions)
Evaluation (Assessing Student Performance)
Hold class discussions and small group discussions about your best chance for
survival.The goal is survival of the group.
Authors
Larry Rose, Science Teacher, TEA Associate, Pleasanton Middle School,
Pleasanton, California
.
Background
Teacher might refer students to SHEBA (see Glacier website) a project now
frozen in to the Arctic Ocean correlating insolation to ice formation- general heat
budget studies.
Resources
Student Reproducible Masters
We
look forward to hearing from you! Please review this activity.
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