Chalk used in school classrooms comes in slender sticks approximately .35 of an inch (nine mm) in diameter and 3.15 in (80 mm) long. Lessons are often presented to entire classes on chalkboards (or blackboards, as they were originally called) using sticks of chalk because this method has proven cheap and easy.

As found in nature, chalk has been used for drawing since prehistoric times, when, according to archaeologists, it helped to create some of the earliest cave drawings. Later, artists of different countries and styles used chalk mainly for sketches, and some such drawings, protected with shellac or a similar substance, have survived. Chalk was first formed into sticks for the convenience of artists. The method was to grind natural chalk to a fine powder, then add water, clay as a binder, and various dry colors. The resultant putty was then rolled into cylinders and dried. Although impurities produce natural...