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.
Discuss ways of keeping an ice cube from melting. Divide the students into groups of three or four. Repeat for the second balloon making sure to use the same amount of water. Mark the balloons with students' names and place them in a freezer. After the water balloons have frozen, return the balloons to each group.