Just in case you aren’t jesting, it’s Over Head Projector.
One of these:
My class in elementary school was the last to have these. After my class they all switched over to a digital camera on an arm, with a projector mounted to the ceiling.
The ones at my school also had about 50 meters of transparency film rolled onto a pair of scrolls, so teachers could write and draw out their lesson plans in advance, and just scroll to the next frame.
As an 8th grade graduation project, me and my two best friends figured out how to hook up a high RPM RC car motor to one of the scrolls, and we drew a 20 second cartoon on a transparency scroll and ran it through the projector. Not groundbreaking work, considering the Lumiere brothers did the exact same thing over a hundred years earlier. But my buddies and I didn’t know anything about actual film at the time, and thought we were original and geniuses and wondered why anybody would use magnetic tape when transparent film was “so simple and intuitive”. Not the sharpest tools in the shed, the three of us.
“The Blackwing of chalks”, he calls it, breathlessly, as if that would carry any meaning to someone from outside the BB community. “We found the best new blackboard markerators since the Mpingo Rod. They’re spine-chillingly great!”
I don’t know what American chalk is like and no doubt this is better stuff but let’s get real here. It’s still bloody chalk. I use it every day and I hate it. It may be the best chalk money can but but it’s still chalk.
Coated chalk has been around since before I was born (1959). Nothing new there. Crayola made it, for god’s sake.
It’s still just chalk. You want to try a slightly creepy experiment? Do what I did once - put a sheet of paper on the table in front of the class and don’t move it. Teach with chalk for an hour, then pick it up and admire the chalk outline. I don’t know what level of aerial calcium carbonate is bad for your lungs but it is probably greater than zero.
