BLUBBER
INTRODUCTION This activity is
appropriate for children in grades K-3. Used in conjunction with
"Feather
Jackets",children can experience a
couple of different ways in which animals are able to keep warm under some
very cold conditions. We first read about this activity in Super
Science Connections.1
PURPOSE This experiment helps
children to understand how one type of insulation, namely blubber, keeps
whales, porpoises, and other sea animals warm even though they live in
extremely cold water.
MATERIALS 2 One-quart
freezer zip-type bags (without the zipper slider)
PREPARATION FOR THE ACTIVITY To prepare a "blubber
bag", put one pound of margarine or shortening (at room temperature) into
a quart plastic freezer bag. Take the other bag and turn it
inside out. Place the second bag inside the first one, making sure
that the zipping components line up correctly (i.e., front of bag #1 to
back of bag #2 and vice versa). Zip the two bags together, making
sure the seal is secure on both front and back. Place your hand into
the inner bag and straighten it out, with 1/2 pound, or 2 sticks, of margarine
on each side of the bag. Knead the bags until the margarine or shortening
is spread evenly inside the two bags.
PROCEDURE Ask the children how they keep warm during the cold winter days. Discuss how animals keep warm, eventually bringing the discussion to how animals that live part or all of their lives in the Polar Regions of the world keep warm. When they come up with the idea of "blubber", ask them if they would like to do an activity to see if blubber, or fat, is really able to keep you warm. Place your container
of ice water on a low desk, so that a child can easily reach into it.
The bucket should only be about 2/3 full to allow for displacement of water
from the childís hands. Ask a child to put the "blubber bag"
on one hand and then to place both hands into the ice water. When
one of his/her hands gets cold, he/she should remove it from the water.
Caution: Some children try to leave their hands in the water for
an especially long time. They may respond better to "Is one hand colder
than the other?" rather than "Take your hand out of the water when it gets
cold." Do not let them keep the unprotected hand in the ice
water for longer than 30 seconds.
EXPLANATION Many marine animals,
including penguins, manatees, and polar bears, as well as whales, porpoises,
and seals, have a layer of fat, which we call "blubber". 3
This blubber acts as an excellent insulator, and the thickness of the blubber
layer varies among species. The Bowhead Whale, the only large whale
that lives exclusively in the Arctic, has a layer of blubber which is up
to 28 inches (70 cm) thick! 2
The "blubber bag" we made is generally no more than 1/2 inch thick, and
yet when a child puts his hand into the bag and submerges that hand in
ice water, his hand will remain warm for a long period of time.
ADDITIONAL SUGGESTIONS If this activity is part of a lesson on "Animals", you may already have available some "temperature-sensitive paper" from "A Color of His Own". You can use that paper to show the class that the hand that was in the blubber bag stayed warm (the paper will change to a different color when held in a warm hand), but the hand which was not protected from the cold water by the blubber bag will be too cold to cause the paper to change color. This lesson can be used in conjunction with a lesson on how feathers insulate birds against the cold (see "Feather Jackets"). For children who would like to learn more about sea animals, the Gulf of Maine Aquarium has an excellent web site for further activities, see http://octopus.gma.org Keeping the blubber bag in your freezer allows you to reuse the same bag many times. Be sure to allow enough time for the margarine to come to room temperature before using it for this activity. REFERENCES 1.
Janice Smith, editor, Super Science Connections, 1995, a publication
from The Institute for Chemical Education (ICE), University of Wisconsin
? Madison, 1101 University Ave, Madison, WI 53706. p.57.
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