An Introduction to Glass Glass is an amorphous substance usually made up of silica fused at high temperatures with borates or phosphates. Glass is also found in nature, as obsidian and tektites. It is not a solid nor a liquid but is a supercooled liquid. Glass is cooled to a rigid state without the occurrence of crystallization. It can appear as transparent, translucent or opaque.

Introduction : continued Molten glass is plastic and can be shaped by means of several techniques. Molten glass is plastic and can be shaped by means of several techniques. Glass was first made before 2000 BC Glass was first made before 2000 BC It is used to make windows, spectacle lens, windscreen, bottles and ornamental items like jewelry It is used to make windows, spectacle lens, windscreen, bottles and ornamental items like jewelry Glass also has architectural and industrial applications. Glass also has architectural and industrial applications.

Properties Hard Hard Transparent Transparent Breaks easily Breaks easily Glass that has a high melting point and does not shrink or expand greatly with changing temperatures. Glass that has a high melting point and does not shrink or expand greatly with changing temperatures. Glass is a poor conductor of both heat and electricity. Glass is a poor conductor of both heat and electricity.

Uses of Glass Windows Windows Lenses Lenses Laboratory apparatus Laboratory apparatus Kitchen ware Kitchen ware For electrical and thermal insulation. For electrical and thermal insulation.

An Introduction to Wood It is a naturally occurring material. It is produced from trees. It is a renewable resource. It has many uses. There are different types of wood. Hard and soft wood.

Properties Hard Hard Poor conductor of heat and electricity Poor conductor of heat and electricity

Uses of wood To make furniture To make furniture To be used as flooring material To be used as flooring material To make boats To make boats For architectural and industrial applications. For architectural and industrial applications. Paper Paper

Quiz What are similarities between glass and wood? What are similarities between glass and wood? What are the differences? What are the differences? Name a few things that can be made of both wood and glass. Name a few things that can be made of both wood and glass.

Thank you Thank you for listening Hope you enjoyed it.