Ah, you kids are so young. Long before Etch A-Sketch, there were several renditions of its predecessor.
The first was just a pressure sensitive board with a piece of transparent film covering the front and only attached at the top. You drew on the film with our old version of a stylus, a stick. Your lines showed up on the film.... and when you were done, you simply peeled the film up from the bottom, erasing all marks, then smoothed it back down for your next drawing.
That wore out soon, and the film got ripped too easily'
So, next they invented one with no film, but rather a semi-hard sheet of rigid plastic on the front. You drew with the same stylus, but to erase, all you had to do was swipe a built-in "slider" tab from left to right, and back again, and the picture was gone.
I think the first of these came out in the mid-50's.