Keeping Warm

SUMMARY:	Learn more about the different types of feathers. In an experiment test the insulating properties of down feathers. This lesson is part of a series. Select this text to learn more about the series and how to extend its usefulness.
OBJECTIVES:	Students will become familiar with bird biology and the important purpose feathers serve.
SUBJECTS:	Science
GRADES:	3-8
LENGTH:	Series

Background: Feathers are unique to birds. They serve several different functions. Vaned feathers cover the bodies, wings, and tails of birds. They are used in flight and camouflage. Down feathers are the small fluffy feathers right next to the body. They keep birds both warm and dry. The down feathers create air pockets around the bird's body which trap the body's warmth and insulate the bird's body. Humans even use down feathers in jackets and sleeping bags.

Materials: Plastic bags, balloons, water, down feathers from domestic ducks and chickens (it is illegal to use native bird feathers), funnels, marking pen, graduated cylinder or measuring cup, and freezer.

How to:

1. Talk about what an insulator is. Discuss ways of keeping an ice cube from melting.
2. Divide the students into groups of three or four. Each group gets 2 plastic bags, 2 balloons, a funnel, and graduated cylinder or measuring cup (the funnel and graduated cylinder or measuring cup could be shared among the class).
3. Each group measures an exact amount of water (just enough to fill the balloon without stretching it too much) and funnels it into the balloon.
4. Repeat for the second balloon making sure to use the same amount of water.
5. Mark the balloons with students' names and place them in a freezer.
6. After the water balloons have frozen, return the balloons to each group. One balloon will be a "control" and be placed in the plastic baggy with nothing surrounding it. The second will be placed in a baggy full of down feathers.
7. Place the bags on a surface where they will be undisturbed. Allow them to sit for 60-90 minutes. While you are waiting have the class discuss what they think will happen to each of the ice balloons.
8. After time is up each group can cut open balloons one at a time, pour the melted water into the measuring device and record. Do this for both balloons.
9. Compare the results. Which balloon gave off more melt water? What does this mean the feathers did for the ice?