Ones that are good insulators of heat or can trap pockets of air to insulate as air is a terrible conductor of heat. E.g. Polystyrene
Flannel sheets are definitely your best bet for keeping warm. It's a heavy, tightly-woven fabric that is ideal for retaining your heat.
Cotton is not as effective as other materials like wool or fleece at keeping you warm because it does not retain heat well and can absorb moisture, making you feel colder.
Materials that are good for keeping things warm are often referred to as "insulators." Common examples include wool, down feathers, fleece, and certain synthetic fabrics like polyester. Additionally, materials such as foam, fiberglass, and certain types of plastics are also effective insulators in various applications. These materials work by reducing heat transfer, keeping warmth contained.
The best shoe covers for snow to keep your feet warm and dry during winter are insulated waterproof boots or shoe covers made of materials like Gore-Tex or neoprene. These materials provide insulation and protection against moisture, keeping your feet comfortable in cold and wet conditions.
Heavycotton sweatshirts or even ones made of wool would be best for keeping a person warm.
There are many materials that will keep you warm. The best ones to use are natural fibers like wool, silk, down, and shearling along with some of the newer space age polymers created to retain warmth.
Lightweight and breathable blankets made from materials like cotton or linen are ideal for hot weather. These materials help regulate body temperature and allow for better airflow, keeping you cool and comfortable during warm nights.
The best materials for making a comfortable and warm sweater for a turtle are soft and insulating fabrics like fleece or wool. These materials will provide warmth and comfort for the turtle while also being gentle on its skin.
A boot with a varied tread to stop you slipping, that is made from natural materials to keep your feet warm.
In a keeping warm investigation, I would include wool, which is known for its excellent insulation properties; down feathers, which trap air and provide warmth; aluminum foil, which reflects heat; and cotton, which is commonly used but less effective in retaining heat compared to the other materials. These materials would allow for a comparative analysis of their thermal properties and effectiveness in retaining warmth.
Keeping warm is not a change - of any sort.
The materials keep you warm by the fabric they are made out of!