Laboratory beakers, constructed of various types of glass, plastic, or metal, may be used for measuring, mixing, pouring, or heating liquids, depending on their construction. The wide-mouth opening of a beaker provides easy access to add ingredients, mix using a stir bar or stir rod, introduce an ion selective electrode or thermometer, and perform other laboratory procedures. A pour spout facilitates controlled pouring into other vessels. Graduated markings on the side, when present, offer less accuracy and precision than graduated cylinders and volumetric flasks.