Here's why:

* Heat: Insulators have a structure where electrons are tightly bound to their atoms. This means they don't easily transfer heat energy from one molecule to another. In contrast, conductors like metals have free electrons that can easily carry heat energy.

* Electricity: Similarly, the tightly bound electrons in insulators make it difficult for an electric current to flow through them. This is because the electrons cannot move freely to carry the charge.

In summary: Wood and air are poor conductors because they resist the flow of both heat and electricity.