Fiberglass helps keep it warm in your house. Leaves can keep animals warm. People cover up with a blanket to stay warm. Snow can insulate. You can use snow to build an igloo.
People insulate houses with styrofoam and fiberglass.
Styrofoam cups keep hot chocolate warm. Straw is made of grass, and some people use it to keep their home warmer. Cardboard is another insulator. It helps ice cream stay cold. Leaves are a good insulator.