Wool, wood, straw, paper, cork, and Styrofoam are poor conductors of heat. The outer electrons in the atoms of these materials are firmly attached. Poor conductors are called insulators.
On the otherhand, solids are better conductors than liquids and liquids are better conductors than gases. Metals are much better conductors than nonmetals. This is because metals have the "loosest" outer electrons, which are free to carry energy by collisions throughout the metal. They are excellent conductors of heat and electricity for this reason. Silver is the best, copper is next, and, among the common metals, aluminum and then iron are next in order.