How do polar animals keep warm?

This half in Science we have been learning about polar animals and how they adapt to survive in the harsh cold climate.
Miss Stratton asked us how polar bears keep warm and we discussed how they have thick fur, which traps air to help insulate them. They also have a layer of fat under their skin called blubber.
We wanted to find out which one of these features was the best insulator.
First we tested how cold the water was by putting our bare hands in and timing to see how long we could keep them in there. We couldn't even make it a minute!
Then we put on a glove and blew air into it, then put our hands back in the water. This time we were able to last around 3 minutes.
Finally we covered our gloved hands in a thick layer of lard, to simulate blubber, and put our hands back in the water. This definitely worked the best as we could keep our hands in for over 6 minutes!
"I found out that the fat was the best insulator because the time we could keep our hand in the water was 6 minutes and 4 seconds. Trapped air was 3 minutes and 5 seconds but the worst was bare hands because its time was not even a minute. For a polar bear, their fat would be blubber and this is the best."
"I found out that the fat was the best because we could keep our hands in the water the longest. So the best insulator for a polar bear is blubber."