Engage Brainstorm ways in which penguins are well-adapted to cold water and icy environments. Demonstrate this with two pieces of flexible card. Try to push one, flat, through a pan of water. Fold another piece five or six times and try pushing that through the water. The smaller, stiffer card, like a penguin's wing, works better.
Most birds have hollow bones to make their bodies light enough to become air-borne.
But the penguins' heavy, solid bones help them float lower in the water. With the help of two student volunteers, demonstrate the difference between hollow bones and solid bones using two toilet paper rolls, one empty the other stuffed with tissue paper. Float an empty can in a bucket of water open end up. Add sand to another can until it sinks slightly. Now push down on both cans.