I know why the original chalkboards were black or at least dark grey - they were made from a type of stone which naturally occurs in those colors. But it’s been a long time since chalkboards were natural stone; I understand these days most are made of porcelain on steel.
And I can see some advantages to dark green over, say, pink. You want the white chalk to really show up on the chalkboard. I also know other colors have been tried, but green seems to have been the most popular for quite some time, given how many are still around in schools.
What I don’t get is why porcelain chalkboards aren’t always black? Wouldn’t it be just as easy to color them black as green? If so, what was the advantage of the green color over black/dark grey?
For a while, when I was a kid, they thought white-on-green was easier on the eyes than white-on-black. IIRC, they made the same sort of posit for computer screens – green text on black instead of white on black. You certainly notice the buildup of erased chaulk on a green board less than you do on a black board. Seems to be phased out, these days.
Back in the day, I used to judge High School science fairs. One girl did a project on what color on what was the most legible. She placed in the fair because her method was very good.
What’s interesting growing up is, I always got the opposite impression. When I was very, very young, white on green was the most common. It seems that the most common these days is white on black. Actually, even more doubleplus common is the use of whiteboards and colored markers.
If you take this subject seriously and want some science behind it, have fun with this:
International Encyclopedia of Ergonomics and Human Factors section of legibility of printed words and distances involving print color versus background color.
I read that the best color combo for readability is dark lettering on white backgound and that’s why California license plates use that combo. They used to be yellow on blue and yellow on black.
My wife’s school uses white dry erase boards these days. Do they still make chalk boards?
True, but think of the generations of kids growing up without having to clean the erasers, or play the “eraser racer” game around the classroom during rainy-day recess, or best of all, hear fingernails scratch across a chalkboard.
All that collective memory, gone like chalk in the wind. . .
Not a whole lot of help on the “why green?” question, but as a useful aside – the old stone blackboards, and in particular the individual portable ones that were about 10"x14", for pupils’ individual classroom work, were called slates because that’s the kind of rock they were made of. Slate fractures or cuts in nice thin slabs, you see, owing to the way it was laid down, making it ideal for the purpose.
I’m a teacher. I find that I do my best board work with chalk. Diagramming, erasing, drawing, etc. all are easier to do with chalk. That’s the main point. They are instructionally superior. As for cleanup, some of the classrooms that I work in now use those white dry erase boards and I dread having to use them. Erasing words on them actually just makes them a bit dimmer, not gone. They smear all over everything and are not easy to clean up. With chalk, if I want to keep my hands clean, I can use one of those little chalk holders. As for clean up, I can erase with the side of my hand, my finger, an eraser, and, if I want to start clean, water. When I leave the classrooms that have dry erase boards, I have to use their special mixture to clean the boards. Takes forever. A real pain in the butt.
FWIW, when I was growing up, green chalboards were apparently glass (since once in a while one would get broken). Also, highway signs in the US can be either brown or green (I suppose this depends on the state).
