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Grade 5 Follow-up Experiment “Cooling Off”
 (From Animals: Mind-Boggling Experiments You Can Turn into Science Fair Projects, Janice VanCleave, John Wiley & Sons, 1993)

Quality Core Curriculum Objectives:
 

Science                       (Inquiry)

            #1 –  Asks questions, makes/records observations, sorts objects, communicates

with others, makes predictions and inferences, makes sketches/diagrams, uses

tables and charts.

            #2 –  Uses books and other media to obtain information.

            #4 –  Actively engages in learning via hands-on/minds-on science activities.

                                       (Life Science)

            #18 –Compares/contrasts animals.  Groups animals by observable characteristics.

Language Arts            (Listening/Speaking)

            #4  -  Recalls and interprets information presented orally.

            #7 –   Paraphrases and discusses information.

            #11 – Increases vocabulary to reflect a growing range of knowledge.

                                        (Reference/Study)

            #60 – Uses dictionaries, thesauri, atlases, almanacs, periodicals and encyclopedias

          to locate information.

            #61 – Uses guide words to locate information.

            #62 – Locates information using the appropriate reference sources.

Vocabulary:  evaporation, panting, conductive heat loss, body temperature

Materials:

            3 x 5-inch index card

            paper towels

            water

            thermometers

            fan

Problem:  How do elephants use their ears to cool their bodies?

Procedure: 

1.      Hold the index card about 4 inches (10 cm) above the skin on your arm.

2.      Quickly fan the index card back and forth about 10 times.

3.      Observe any cooling of your skin due to the fanning paper.

4.      Wet the paper towel with water.

5.      Rub the wet towel over the surface of your arm.

6.      Hold the index card about 4 inches above your wet arm.

7.      Quickly fan the index card back and forth about 10 times.

8.      Again, observe any cooling effect on the skin.

Results:

The wet skin feels cooler when fanned than does the dry skin.

Why?

The cooling effect is due to the evaporation of the water from the skin.  Evaporation occurs when a liquid absorbs enough heat energy to change from a liquid to a gas.  The water takes energy away from the skin when it evaporates, causing the skin to cool.  Elephants use their trunks to spray themselves with water; then they fan their bodies with their large ears.  The fanning of their ears, like the index card, increases the flow of air across the skin.  The moving air speeds the evaporation of the water and, thus, aids in the cooling of the skin.

Let’s Explore:

*  Is it the moving air or the evaporation of the water that cools the skin?  Demonstrate the cooling effect of evaporation by placing two thermometers on a table.  Record the temperature shown on each thermometer as your baseline.  Wet a paper towel with water and place it over the bulb of one of the thermometers.  Ask the students to predict which thermometer will cool faster and by how much.  Place a fan so that it blows across the bulbs of both thermometers.  Wait five minutes, then record the temperature shown on each thermometer.  How did the students’ predictions match the results?

*  Would an elephant with bigger ears keep cooler?  Determine the cooling effect of larger ears by repeating the experiment three times.  Each time, increase the size of the index card or other piece of paper. 

*  Is the elephant’s behavior instinctive or learned?  Or is it both?

*  What purpose do the sweat glands of humans serve?

*  Dogs and many other mammals do not have sweat glands in their skin to bring moisture to the surface to evaporate.  They stick out their long, moist tongues and quickly draw air in through their noses and out their mouths.  This is called panting.  How does panting cool their bodies?

*  Polar bears and humans have about the same body temperature of 98.6 degrees Fahrenheit (37 degrees Celsius), but polar bears often overheat because of their thick fur, skin, and fatty blubber.  When a bear’s body temperature begins to rise, the bear cools off by turning its face or its rear end into the wind.  This cooling method is an example of conductive heat loss.  (Do you think this is a learned or instinctive behavior?  Why?)  In what other ways is heat lost from the bear’s body by conduction?  What color is a polar bear’s hair?  What color is its skin?  Find out more about the bear’s hair and skin.

*  Can you think of any other animals that do things to regulate their body temperature?  Do warm-blooded animals differ from cold-blooded animals in such behaviors?
 
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