Chalk

As chalk disappears from the classroom, and images of blackboards, chalk dust, and clapping erasers are replaced by images of whiteboards, Magic Markers, and dry erasers, and even these are replaced by computer screens and projectors, sticks of chalk and blackboards (which are actually usually greenboards in grade schools and high schools and brownboards in universities) remain icons in our collective educational imagination, as persistent as clip art graphics of little red school houses, school bells, and an apple for the teacher.

Here is Wikipedia’s definition of “chalk”, and a poetic little history of its uses and its replacements:

“Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. It forms under relatively deep marine conditions from the gradual accumulation of minute calcite plates (coccoliths) shed from micro-organisms called coccolithophores…

“Blackboard chalk is a substance used for drawing on rough surfaces, as it readily crumbles leaving particles that stick loosely to these surfaces. Although traditionally composed of natural chalk, modern blackboard chalk is generally made from the mineral gypsum (calcium sulfate), often supplied in sticks of compressed powder about 10 cm long.

"In lawn tennis, powdered chalk was used to mark the boundary lines of the court. This gives the advantage that, if the ball hits the line, a cloud of chalk or pigment dust can be seen. Nowadays the substance used is mostly titanium dioxide.

“In gymnastics, rock-climbing, billiards, bouldering, weight-lifting and tug of war, chalk—now usually magnesium carbonate—is applied to the hands to prevent slipping.

“Tailor's chalk is traditionally a hard chalk used to make temporary markings on cloth, mainly by tailors. Nowadays it is usually made from talc (magnesium silicate).

“Sidewalk chalk is made of sticks of colored chalk (now mostly gypsum) used to draw on sidewalks, streets, and driveways. It is often done by children, but in many cities, talented adult artists create masterpieces on the walkways.”

Source: Wikipedia, March 2008

Query: Do virtual fingernails on on-line blackboards make us wince in cyberspace?

Arnold Aprill
Founding and Creative Director
Chicago Arts Partnerships in Education
www.capeweb.org