I have often wondered hoe blackboards came to be so widely used.
Excerpted from Blackboard: A Personal History of the Classroom by Lewis Buzbee. Out now from Graywolf Press.
The blackboard is a recent innovation. Erasable slates, a cheap but durable substitute for costly paper and ink, had been in use for centuries. Students could practice reading and writing and math on their slates, in the classroom or at home. But it wasn’t until 1800 that James Pillans, headmaster of the Old High School of Edinburgh, Scotland, wanting to offer geography lessons to his students that required larger maps, connected a number of smaller slates into a single grand field. And in 1801, George Baron, a West Point mathematics teacher, also began to use a board of connected slates, the most effective way, he found, to illustrate complex formulas to a larger audience.
Although the term blackboard did not appear until 1815, the use of these cobbled-together slates spread quickly; by 1809, every public school in Philadelphia was using them. Teachers now had a flexible and versatile visual aid, a device that was both textbook and blank page, as well as a laboratory, and most importantly, a point of focus. The blackboard illustrates and is illustrated. Students no longer simply listened to the teacher; they had reason to look up from their desks.
Like many of the best tools, the blackboard is a simple machine, and in the 19th century, in rural areas particularly, it was often made from scratch, rough pine boards nailed together and covered with a mixture of egg whites and the carbon leavings from charred potatoes. By 1840 blackboards were manufactured commercially, smoothly planed wooden boards coated with a thick, porcelain-based paint. In the 20th century, blackboards were mostly porcelain-enameled steel and could last 10 to 20 years. Imagine that, a classroom machine so durable and flexible. In my daughter’s schools, computers, scads of them, are replaced every two to three years.
While black was long the traditional color for blackboards, a green porcelain surface, first used around 1930, cut down on glare, and as this green surface became more common, the word chalkboard came into use.
Chalk, of course, predates the blackboard. The chalk with which we write on boards isn’t actual chalk but gypsum, the dihydrate form of calcium sulfate. Gypsum is found naturally and can be used straight out of the ground in big chunks, but it can also be pulverized, colored, and then compressed into cylinders. My most important high school teacher, Mrs. Jouthas, used a variety of neon-colored chalk to help us differentiate the parts of speech, or follow the rhythms of a Mark Twain paragraph.
The last time I saw a real blackboard in a classroom was during a visit to a still-functioning one-room schoolhouse near Hollister, California. The blackboard had been faithfully reconstructed as a souvenir of the school’s past, while the teacher and students mainly used the whiteboards that covered the other walls. Whiteboards are the rule these days, and all to the better, it seems, if only for their lack of screeching. But the whiteboard disallows a long-standing classroom rite: cleaning the erasers.
Slates and chalkboards were often cleaned with dry rags, and no doubt sleeves, but in the late 19th century, erasers were developed for this task, blocks of wood (later pressed cardboard) covered with tufted felt, usually black or gray. These erasers needed regular cleaning to knock loose all that chalk crammed into the felt’s pores, and while it was occasionally a punishment to clean the erasers, it was most often, at my school, a privilege. Often it was the student with the highest score on a test who was invited to pound two erasers together, happy in a billowing cloud of quite possibly lung-damaging dust.
Another aspect of this privilege was cleaning the blackboard itself, wiping it with a slightly damp rag to a chalkless sheen, making it once again a tabula rasa. But the real joy rested with the erasers, the unalloyed childhood love of making a sanctioned mess, as well as permission to hit things together really hard. But I cannot overlook the “teacher’s pet” factor. When I was asked to clean Miss Babb’s erasers, it was for her that I did so.