Below Zero Activities
Age: K - 6
Subjects: Language Arts, Mathematics, Science, Social Studies
Skills: analysis, application, communication, comparing, description,
discussion, matching, measuring, reading, research, small
group work, inference, brainstorming, problem solving
Duration: two to three 40-minute periods
Group Size: 20 - 30 students
Setting: indoor and outdoors
Conceptual Framework References: 4a, 4b, 4c, 4d, 5a, 5c
Key Vocabulary: guard hair, under hair, subcutaneous fat,
diet, adaptations, pelage, chionophile, kamiks, parka, pleistocene
Objective
Students will be able to:
1) List some of the polar bear's adaptations to an arctic
climate.
2) Create a winter outfit for themselves based on their findings
about polar bears.
3) Understand and explain the biology of keeping warm.
Method
Students research and determine the appropriate
winter clothing required by humans.
Background
Polar bears have lived in their Arctic environment
since they evolved from coastal grizzly bears during the late
Pleistocene Age approximately 200,000 years ago. During this
evolution, polar bears developed anatomical, physiological
and behavioral adaptations to life in a frozen land. Species
like polar bears, which have adapted specifically for winter
survival, are called chionophiles, latin for snow lovers.
The polar bear is a sensible winter dresser,
thanks to its three "coats". The first is a layer of oily,
water-repellent guard hairs. Though these appear white or
creamy yellow in colour, they are actually transparent and
hollow. Their colour is the reflection of visible light. These
hairs reflect radiant heat from the sun down to the bear's
black skin. The next coat is a layer of dense underfur which
snuggles against the animal's skin much like long underwear.
Beneath the black skin is the final coat, a thick layer of
insulating subcutaneous fat which keeps the bear's vital core
warm.
The polar bear has many other sensible winter
adaptations. It's well-furred ears and tail are relatively
small, and so less likely to be frostbitten. It's wide, densely-furred
and noiseless feet with their webbed toes, can't be beat for
silently stalking prey, keeping warm, walking in snow and
swimming. To avoid a chill, polar bears also shake themselves
vigorously as soon as they climb out of water.
In winter, polar bears eat mostly seals, particularly
ringed seals. Often they leave the meat untouched and devour
the energy-rich blubber instead. (Species like Arctic foxes
and ravens that follow the bears gobble up the leftovers!)
(Mammals of the Canadian Wild.) Polar bears can digest
fat and protein very efficiently. Depending on how active
they are, the temperature, and whether they are feeding or
starving, their metabolic rate fluctuates greatly. Females
fast for eight months during winter while they are pregnant
and giving birth! They prepare for this by gorging on seals
from April until early July, and boosting their body fat to
50 per cent or more. (National Geographic, Jan. 1998, "Polar
Bears".)
Arctic summers can be way too hot for these
well-insulated bears! Summer dens have been found where polar
bears dig deep into the permafrost to cool off. It is thought
that some of these dens may have been used for hundreds of
years.
Traditionally, Inuit have used the polar bear
to their advantage. Skins were used to make mittens, kamiks
or boots, and trousers. Sometimes, overboots were made with
the fur side out to muffle their footsteps while hunting seals.
Oil from the pelage or coat is used to grease sledge runners
for an easier glide over the snow. Even today, we can learn
a lot from animals about dressing and moving around in cold
and snow.
Your human body has its own set of survival
techniques. As the temperature drops, your body's main objective
is to keep your most important organs warm, the brain, heart
and lungs. Blood vessels at the skin's surface contract to
keep the warm blood deep inside your body core. This is why
feet and hands feel chilly first, as warm blood has moved
away from them. The body loses 40 per cent of its heat through
the extremities -- head, hands, feet.
Just like a wood stove that has to be stoked
with fuel, your body needs fuel for warmth, too. Instead of
wood, however, it burns food and fat reserves. In the winter,
you need to eat more energy-rich food than in summer. The
body can also produce heat by shivering. This gets muscles
moving, helping them to warm up. And of course, the more you
move the warmer you will become.
Did you know that when you wear a hat, you're
actually keeping your feet warm? That's because if your head
is uncovered, more blood is moved to your noggin in order
to keep your brain warm. Once your head is snug and warm,
the blood can circulate to less essential spots, like your
feet.
It's smart to wear loose-fitting boots that
have room for an extra layer of socks. The loose fit will
also let blood circulate more freely.
Perhaps you've noticed that mittens are cozier
than gloves. Fingers stay warmer if they can snuggle up together.
Mitts trap air, too, and add insulation. Layers work best,
water or wind-proof layer over a thinner mitt will keep fingers
toasty and dry.
Layer your clothing, too. This creates air pockets
that trap warm air close to the body. Like the polar bear's
coats, you should have an insulating layer close to the skin
and an outer layer that is wind and water-proof.
Materials
scissors; large sheets of brown craft paper
or coloured kraft paper; pencils; crayons; samples of various
furry pelts (optional); pictures of various furry animals;
longjohns; thermometers; boots; liners; mukluks; parkas; kamiks;
mitts; toques; scarves; light sweater; body shirt; handbook
from St. John's Ambulance, Girl Guides or Boy Scouts for winter
gear suggestions; shell nylon jacket; and pictures of foods
from the various food groups (for one of the activity variations.)
Procedure
1) Investigate different types of hairs using
the polar bear or caribou as an example. Explain how guard
or outer hairs are long, waterproof, coarse and hollow (the
latter can be seen under a microscope by slicing a caribou
hair on the diagonal). Then discuss how the under-fur is soft,
close and dense (like a cotton ball). It traps air for insulation.
2) Investigate hair and other physical features
that help the polar bear to survive. For instance, through
pictures or pelts, discuss what parts of the polar bear are
covered with hair and how that is useful in arctic conditions.
Also discuss how the bear's wide feet help it to walk on snow.
3) Discuss why polar bears need layers of fat,
often 3-10 cm thick.
4) Brainstorm what kinds of clothing we need
to keep us cozy in very cold weather. Divide students into
groups of four and give each group a body part to dress: head,
feet, body, or hands. Give groups time to plan what clothes
to bring for the following day.
5) Next day, trace an outline of a willing volunteer
lying down on the brown kraft paper. Next, cut out the body
outline, then have each group place the most suitable clothing
on the outline. Discuss the clothing choices.
6) The following day, have students dress for
the outdoors based on what they have learned so far. Once
outside, have some students stand still for 15 minutes and
observe how their bodies react. At the same time, the rest
of the class can be constantly moving around. After the 15
minutes is up, have students in both groups measure their
skin temperature inside their clothes and also where it is
exposed to air. Back in the classroom, discuss the body reactions
for each group. Ask students if they would make any modifications
to their clothing choices, and why.
Variations
For K - Gr. 3:
1) Make a list of winter clothing -- sweaters, snowsuits,
toques, etc.
2) Have students match each word to the correct
item of clothing.
3) Have students match clothing to the proper
body part.
4) Name some nutritious, high-energy foods that
polar bears or humans eat.
For Gr. 4 - 6:
1) Have students research a variety of clothing fibres and
their effectiveness in a cold environment.
2) Have students research a list of nutritious,
high-energy foods. Then have them plan a menu and prepare
a high-energy winter lunch for themselves or another class.
Extensions
1) Test white and black objects for heat retention.
2) Test cotton, wood, and synthetics to determine
which remains the warmest when wet.
3) Invite an elder, hunter or a museum staff
person to demonstrate traditional winter clothing to students.
Evaluation
1) Students will demonstrate what they have
learned by dressing appropriately for outdoor conditions.
2) Describe at least four ways that the polar
bear has adapted in order to survive winter.
Copyright 1998 by the Canadian Wildlife Federation.
All rights reserved.
|
Project
WILD