Using the picture book Over and Under the Snow by Kate Messner https://www.youtube.com/watch?v=UYUQzzULHg4 I would start by reading this book with the children in senior infants. We would look at the following animals in the story; the squirrel, horned owl, shrew, deer, mice, moles, hare, bullhorn frogs, bear and chimp monk. We would discuss about how the animals in the story keep themselves warm in the snow such as their feathers/fur/fat and grease layer on their skin. We would also categorise the animals into two groups; the animals that live over the snow and those under the snow.
We could discuss about how there are different kinds of weather around the world and how animals have different features to keep them warm.
We could talk about the animals that live at the North Pole and the South Pole. Ask the children know any of the animals that live in cold places. Show them photographs of the polar bear and penguin. How do these animals keep themselves warm. Discuss the ideas that the children put forward. The children could also categorise the animals that live over and under the snow in these areas.