Which materials could typically be classified as thermal insulators?

Foam is commonly classified as a thermal insulator due to its unique structure, which contains numerous air pockets that significantly reduce heat transfer. This characteristic makes it an effective barrier against thermal energy moving through conduction and convection. The low density and ability to trap air contribute to its insulating properties, allowing foam to minimize heat loss in a variety of applications, such as in building insulation, thermal containers, and protective gear.

In contrast, materials like copper and other metals are typically good conductors of heat and would not be effective as thermal insulators. Ceramics can have insulating properties, but they are not as efficient as foam in terms of weight and flexibility for insulation purposes. Therefore, foam stands out as a typical example of a thermal insulator due to its design and function in reducing heat transfer.