How Cold Is Cold?

How is traditional knowledge still important today?

Science, social science

To manage their own bodies optimally during the Iditarod, mushers racing must have a high calorie intake (eat well), stay well-insulated and stay dry. The human body produces body-heat by burning calories (food) and the blood flow to the skin is increased and decreased to regulate our body heat. About 5.3 quarts (5 liters) of blood circulates through our vascular network, which if laid out in straight tubing, would cover a distance equivalent to nearly 60 miles (100 km). When the body experience a drop in temperature, it limits blood circulation in the extremities of the body to preserve heat for the body core (brain and heart). Eventually the body shuts down, resulting in death. This slowdown process is what we know as hypothermia. Keeping dry is as important as keeping warm. As the body burns energy during physical exertion, it creates heat. It then produces sweat, which provides a cooling effect as it evaporates. During strenuous activity an aunt can loose up to 10 liters of water through evaporation the skin. A sweaty person loose heat rapidly in frigid temperatures. Clothing optimally designed for Arctic travel result from the traditional knowledge of the Native Arctic peoples: such as the long length of the outer jackets / anoraks, the fur ruff protecting the face and the soft hide boots also known as mukluks. What is the science behind the efficiency of mukluks?

Scroll down for activity! Or click to download Cold is Cold Activity (PDF)



1) Share with students that during the Iditarod temperatures often drop to minus 40 (actual temperature). Ask students if they have experienced such cold, and if not what is the coldest temperatures they have experienced and stayed warm in? Why do they think they get cold? As a class brainstorm and record, what are strategies for the body to stay warm?

2) Draw a figure on the black board (nothing fancy necessary, a cookie man will do), add a heart and a brain. Now ask the students what they think are the most important organs for our body to protect in order for us to survive? Circle the brain and the heart (the answer), and put a large circle around the upper body (chest region and head, not including the arms). Explain that this is called the core, and that our body in extreme cold temperatures will do whatever is necessary to keep this core warm.

3) Share with students that our body produces body heat by burning calories (food) and that the blood serves as the method to distribute our body heat.

Our bodies pump about 5.3 quarts of blood through our blood circulation system, which if laid out as a straight tubing would cover a distance more than twice around the earth! So, as soon as the body temperature starts to drop, the body simply goes into “keep-the-core-warm-mode” by slowing down the delivery of blood to the extremities in the body…

Ask students what they would consider to be the extremities of their body? Have they ever heard anybody say: ” my hands and feet are always cold!”? Can they now think of an explanation for this?

4) To illustrates what happens and how it feels when your body begins to cool down, the students will test how exposure to cold affects their dexterity.

Divide students into groups of three. Each group assigns a time keeper and a recorder. Give each group a pan of ice water to be maintained at 50 degrees Fahrenheit. Spread out twenty pennies on the desk and have students take turns picking them up and placing them in a plastic cup. Have them time how long it takes for each trial. repeat the experiment, but this time, instruct each student to first hold his or her hand in the ice water for 60 seconds. As a class discuss the results (graph if desired) and identify the specific trends.

5) Now ask students to do twenty rapid jumping jacks. Do they get warm? What happens to athletes when they work really hard? Do they sweat? Discuss with students how keeping dry (not sweating) is as important as keeping warm when it comes to survival and comfort in the Arctic.

Ask students how they think this is connected with that it is important that the materials worn in very cold temperatures can breathe like our skin (or animal hide)?

6) Divide students into teams of two. Each team assign a “test person” and a “scientist.” The scientist cut a plastic bag into a single layered square, large enough to fit comfortably around the forearm of the test person, then places the piece of plastic around the forearm and tapes it securely (but not too tight) at the top and bottom.

The test person exercise for at least five minutes for example by running up and down stairs in intervals of two minutes of running alternating with one minute walking; or by alternately walking and doing jumping jacks on the spot.

Respiration rate and pulse should be recorded at the beginning and the end of the experiment. At the end of the experiment the scientist records whether the skin of the test person released any water condensation overall? Then when taking the plastic off, note the moisture level of the skin that was under the plastic as compared to skin exposed to air during the exercise!? Discuss the results.

7) The mukluks that Joar wears during the Iditarod is made of untreated moose hide with a flexible runner sole (that does not freeze). This is a design by the Native Arctic people. Why do students think Joar wears these kinds of boots — brainstorm as a group why mukluks (made of animal hide) are optimal for traveling in the cold? Have students draw conclusions and list the benefits of the mukluk which should include the following:

– mukluks can breathe (keeps feet dry)
– mukluks are flexible (movement of foot is not restricted which means blood circulation is constantly stimulated when moving)
– mukluks are lightweight (not tiring even over long distance)

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