I bought this for $1 at an estate sale a couple weekends ago. I told my kids this was our generation's iPad. It required no electricity or wifi and cost only 36 cents. The only thing powering it was imagination.
A close cousin to the Etch-a-Sketch, this simple device required no knobs to turn, just a red plastic stylus (unfortunately lost on mine). For those of you too young to remember these, it was simply a piece of gray plastic over a black waxy backing. When drawn on with the provided magic pencil, a picture could be drawn. To erase it, you simple lifted the paper and it was ready for another drawing.
Retro toy maker Schylling still sells their version of the Magic Slate and does oldtimecandy.