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COPYRIGHT 2006 National Science Teachers Association
Byline: Juanita Urban-Rich
Every time I visit an elementary classroom and mention that I'm an oceanographer who conducts research in the Arctic and Antarctic, the room fills with oohs and ahhs. Whatever their age group, children are fascinated with polar bears, penguins, whales, and other polar-related things. They are intrigued by the idea of survival in the extreme cold. Invariably, students ask: How cold is it there? How does anything live there when it is so cold?
I decided to develop an activity to help students explore these questions more fully. "The Polar Insulation Investigation" builds on students' natural interest in "things polar" and introduces them to animal adaptations in a unique way. The aim of the exploration is to determine the role of animal coverings (e.g., blubber, fur, and feathers) and to see which is the best insulator. It also provides an opportunity to develop and practice skills for measuring temperature.
I've conducted variations of this exploration many times with children from kindergarten through grade five. Younger students can grasp the big picture that temperature can vary a lot between regions of the world and that animals have adaptations such as "coverings" to help them survive. Exploring these concepts lets students develop science inquiry and process skills. Older students can take these ideas further, exploring ideas behind investigation design and making connections to mathematics through graphing, interpreting data, and measuring temperature.
The experience described here was conducted with a group of third-grade students.
Introducing the Lesson
I started this lesson with a review of thermometer use. These students were not yet comfortable with the use of the Celsius temperature scale, so we conducted our discussion using Farenheit degrees, with only brief mention of Celsius degrees. I showed students four illustrations of the same thermometer, and students practiced reading temperatures by pointing to different temperatures on the illustrations.
Next, I asked students to indicate the classroom's temperature on one of the thermometers, using red crayons or pencil. Then they predicted and colored the temperatures of ice water and boiling water. Most students predicted an accurate room temperature of 70*F, but there was a range in temperatures for ice water from 0-40*F, and a range for the temperature of boiling water from 100-200*F. Afterward, we discussed their reasoning for their predictions. Most students knew an average room temperature because they see or help with the thermostat at home; but while they know that freezing water is cold and boiling water is hot, many students did not know at what temperature this occurs.
I explained that fresh water freezes at 0*C (32*F), sea water freezes at -1.4*C (28.5*F), and that the water around the ice would be close to this temperature. I told them water boils at 100*C (212*F). Then, we constructed a number line to use for reference later in the lesson and plotted these values on the line.
Next, students predicted the temperatures in the Arctic and Antarctic. Students were surprised when I told them that temperatures there range from -56 to 15*C (-70 to 60*F). We calculated that for an average day in April there was about a 90*F difference between a classroom and a polar region!
Next, we discussed what animals live in polar areas-polar bears, penguins, whales, seals, walruses, and people-and how they must survive in the cold temperatures of the Arctic and Antarctic. We came up with four kinds of animal coverings to work with in our investigation:
Fur (polar bear),
Feathers (penguins),
Blubber (whales, seals, and walruses), and
Nothing (this would function as our control).
Our objective was to examine how animals keep warm in a cold environment. Students recorded their prediction for which covering would keep an animal the warmest at the top of their data log sheet (Figure 1).
Figure 1.
Data Log Sheet.
Experiment: What effect does a covering have for mammals or birds in the Arctic?
Name:
Prediction:
Covering Type
Temp. Before
Temp. After
Difference
Most students predicted "blubber" because "whales live in the ocean and they use blubber, and the polar oceans are always cold" or because "blubber is thicker than feathers or fur."
Measuring and Testing
This activity is a modification of "blubber bags" from the Marine Mammal Center in San Francisco (see Internet Resources). For this activity, you'll need:
A large container full of ice water (any bucket large enough to hold a half gallon of water and several trays of ice cubes will work),
A bottle of hot water (representing a warm-blooded animal) for each student,
One quart-size sealable plastic bag per student,
Two snack-size sealable plastic bags per student,
Fur and feathers (available at craft stores), and
A jar of solid vegetable shortening to represent blubber.
First, each student selected a covering for their animal-fur, feathers, or blubber-and recorded it on their worksheet. (Younger students can work in pairs.) Then, each student received a small, sealed plastic water bottle filled with water that ranged from around 90-100*F. I was aiming for 98*F (mammal body temperature). I had filled the bottles myself from an insulated cooler that I had filled with boiling water several hours earlier. Be sure to fill the bottles with the hot water in advance when students are not around.
Students measured the temperature of the water in their "animal" and recorded the temperature on the data log sheet. Younger students (K-2) can measure the temperature using temperature strips like those used on aquariums-these strips show temperature in whole numbers and use color codes (these can be purchased at any pet store or through many educational supply stores), while older students (grades 3-5) use thermometers.
Explore the topic of Polar Climates Grades 5-8While students were taking these measurements, I distributed the rest of the materials to make the bags. (For younger students (K-2), I prepare the bags in advance, but older students can make the bags themselves.) Each student received their chosen "covering" and two snack-size bags. In one bag they placed either a small piece of fur, enough feathers to fill the bag, or about 2 tablespoons solid vegetable shortening. They turned the second snack-size bag inside-out and placed the inside-out bag into the bag with the covering so that the fur, feathers, or blubber was sandwiched between the two bags. Then, students added the water bottle, representing the animal, to the inner bag and sealed the two bags together. Finally, students put this sealed "animal bag" into a larger (quart-size) sealable plastic bag containing a few rocks. (The rocks ensured that the "covered animal" will be totally submerged when it is later placed in a tank of ice water.) We kept one water bottle without a covering as our control.
Explore the topic of Polar Climates Grades K-4Next, students placed their "covered animal" in the tank with ice water, submerging it for 30 seconds. When the time was up, they removed the animal and again measured the temperature of the water inside the bottle, recording this information on their data log sheet. In general, students could tell just by feeling the bottle that something happened to the water. Typical comments included, "my water's cold now," "it didn't change much," or "how come mine didn't change like theirs?"
Working With Data
After students collected the data, they calculated how much temperature their "animal" lost when it was submerged in the ice water. Students recorded the difference in temperatures on their individual data log sheet as well as on a class data log sheet-a table drawn on the board or a large piece of paper with columns for each covering.
Using the data from the class log sheet, students then calculated the average temperature lost for each covering. (For younger students, I calculate this number. I tell students that all animals are different and that some animals will lose a little more or a little less heat than others, but this average number is the value that represents what that group of animals lost. With kindergarten students, we look at the change in color on the thermometer strips-they usually go from red to green-and I give them the temperature value for these colors.)
Then, together, we created a class graph depicting the average temperature lost for each kind of covering (Figure 2).
As we discussed the graph, I explained that the average temperature loss for the animal from the class data is a more accurate picture of how much temperature is lost than an individual student's data for that animal.
We discussed that the actual amount of temperature lost depends upon the initial temperature of the water in the bottle. And, during the class period, the water temperature decreased in the bottles. We discussed why this happened, and that this is the reason scientists repeat experiments before they draw conclusions.
This conversation started when a student observed, "My animal lost 7* but someone else's only lost 3*, why?" We held a group discussion of what is different between each animal (e.g., initial water temperature) and then discussed experimental errors (e.g., The 30-second submersion-was this always done exactly or did some leave it for 35 seconds? Were all the thermometers or coverings the same? etc.) Students usually end up listing ways that they did the experiment differently.
Drawing Conclusions
Referring to the class graph, students concluded that the feathers worked best at keeping an animal warm in polar waters. Finally, students wrote a paragraph on which covering worked best and why they thought so. Examples included:
"I think feathers were warmer because there are two layers of feathers. Blubber came next because blubber's like rubber. Fur was next because the fur had only one layer of fur."
"I think feathers came in first because they are a thick, heavy coat and the feathers kept piling over each other. Blubber: I think blubber came in second because it soft and very heavy coat of whale. Fur: I think fur came in third because the fur isn't that heavy, so that's why fur came in third."
To conclude the experience, we compared the class findings to individual predictions and answered additional questions. Some students wondered what would happen if you combined coverings (e.g., blubber and fur or blubber and feathers), so we talked about a future investigation. We also talked about seasonal adaptation by animals, such as the increase in blubber in polar bears, seals, and local animals (squirrels) before winter.
Interdisciplinary Expansions
Our animal covering investigation discussion quickly evolved into an interdisciplinary one. Students began wondering if coverings would make an animal too hot if they were moved to a zoo in a warmer environment. This led to a discussion about habitats and how zoos try to build habitats that will let the animals survive even if the climate around them is different from where they live in nature.
Discussion also flowed to wonder about the different types of coats humans wear in winter depending upon their location, such as down coats or coats with fur lining or thin cloth coats. The fur-lined coats comments led into cultural questions about Inuit people and their clothing, quickly moving us from science to social studies. We talked about how people use the resources around them to create clothing or houses that let them survive in an area. While many people today use synthetic material for their clothing, this was not always the case, and we discussed why people used what they did to make clothes.
Students' enthusiasm as we discussed the investigation and their thoughtful follow-up questions demonstrated to me the experience was a real success. Students were totally engaged in the learning process and making connections to other subjects-just as inquiring scientists do.
Juanita Urban-Rich (juanita.urban-rich@umb.edu) is an associate professor of zooplankton ecology at University of Massachusetts Boston in Boston, Massachusetts.
Resources
National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academy Press.
Internet
Blubber Experiment www.marinemammalcenter.org/learning/education/teacher_resources/blubber.asp
Connecting to the Standards This article relates to the following National Science Education Standards (NRC 1996): Content Standards Grades K-4 Standard C: Life Science The characteristics of organisms Organisms and environment
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