Mortar and pestle

You may have one of these in your kitchen for use in grinding spices.

Students sometimes confuse the two parts - the mortar is the bowl and the pestle is the grinder. We use them in chemistry for grinding up powders. Finer powders react faster. They may also be used to extract substances from plant material. In the latter case it helps to add some sand to the mortar to help break up the plant cells.