Some animals possess furry coats that help them stay warm in the water. Certain species, such as muskrats, have double coats for extra protection from cold waters. Kindergartners can understand how this phenomenon works, through activities about furry coats. Give kids furry coats to wear inside the classroom, and ask them whether or not they feel warmer with the coats on. Another lesson plan for furry coats involves the kindergartners drawing pictures of animals with lots of hair and demonstrating, in a picture, that the animal can swim in the water because of the oils in the coat.
Blubber is one physical trait that allows some oceanic animals to stay warm in the water. As an activity, you can identify and study the blubbery animals that can successfully swim in the cold, such as walruses, penguins, whales and sea lions. Then, demonstrate how blubber works through a class exercise. One exercise idea is for kids to stick their hands inside of plastic sandwich bags and tie the bags at the wrist with tape. The kids place their covered hands inside a container of cold water. Have children cover their hands with shortening, to mimic blubber. When the kids dip their hands into the cold water again, ask them whether the water still feels as cold with all of the fat surrounding their hands.
Another way that animals stay warm in the water is through movement. When animals move around, such as by swimming, chasing their prey or escaping predators, their body heat rises from the motion and they remain warmer. Such a lesson can be demonstrated by having the kindergarten class sit still, then move around. Kids can do jumping jacks, push ups or other forms of movement to stimulate the body. After a minute or so of hype, ask the class if they feel hotter now. Most likely they are, and this relates to how animals stay warm in cold water.
The concept of warm-blooded and cold-blooded animals may be complicated for kindergartners, but you can break down the idea so they understand how certain warm-blooded animals stay warm in the water. Cold-blooded animals have a harder time staying warm in cold environments, because their internal body temperature adapts to the exterior climate. So, if a cold-blooded animal is in cold water, its body temperature also becomes cold, and the animal has a harder time staying warm. Warm-blooded animals, on the other hand, have internal mechanisms in place for balancing the body temperature. For instance, warm blooded animals shiver if they are cold, to generate heat, which warms them up. This is true for warm-blooded animals that go into the water, too.