STR Micro-Lesson: Stay Warm
(click here to see the full image)
Question
This image may look like grandpa's beard, but if it was, grandpa would likely live in Central Asia at high elevation and his "beard" would help grandpa to survive in temperatures as low as -40 degrees C. What is it?
Answer
This is an image of wool from a yak, viewed at 50x with a handheld digital microscope such as STR’s “Scope on a Rope”. Wool has special properties which help keep the animal that grows it warm in harsh winter weather. The natural structure of wool includes a lot of space for air between the fibers. These air pockets (which are clearly seen when magnified) are warmed by the body and/or from the heat of the sun forming a barrier against the colder air outside the fabric layer.
Micro-Lesson* Plan
Topic: Properties of Fabric
Download the enlarged version of the image above and show it to your class (using a projector or a color printout). Ask the question just below the image. You may wish to give hints.
Once you have elicited or presented the answer, explain to students that animal and human bodies have a range of heat and cold limitations for survival and comfort. Animals have hair, fur, or feathers to help maintain body temperature while humans mainly use clothing. Ask students to suggest reasons why animal fur and clothes on people help keep them warm. Make a list of the suggested reasons.
Have the students examine different fabrics available in the room. Ask the students how warm they think each fabric might keep them on a cold day and to hypothesize why? Explain that the existence of air and movement of air near the skin are primary factors for keeping warm. Have students makes a list of fabric characteristics that would keep people the most warm. From there you can move on to other topics including the importance of insulating other things like houses and water pipes, and even describing the role of the earth’s atmosphere to insulate it from the cold of space. These links may be helpful:
Physical and Chemical Properties of Wool
The Yak In Relation To Its Environment
More…
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Comments?
Let us know what you think of this lesson idea, or if you have suggestions for more STR Micro-lessons.
*STR Micro-Lessons™ are designed as "plug-ins" to support and augment standards-based science teaching and learning. For complete lessons using the Scope on a Rope handheld digital microscope, see the STR Teacher Resources page.
