1.   A brittle material breaks suddenly, rather than deforming smoothly, when forced beyond a critical value.

2.   Glass that is near room temperature is a familiar brittle material, and modeling clay is obviously ductile.

3.   The conventional image of a ceramic is of a hard brittle material used to make items such as crockery and tiles.

4.   Polymers such as polystyrene and poly with a high E at ambient temperatures fall into the category of hard brittle materials which break before point Y is reached.

5.   The rippling folds exposed in one rock cutaway are a graceful show of how seemingly brittle material can flow, given enough time and heat.