system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do etch-a-sketch’s work?
gpt
Contrary to popular belief, the stylus you use to draw doesn't draw the line.

The inside "screen" of the toy is coated in aluminum powder, and when the stylus scrapes it out, it reveals the darkness inside the toy. When you shake it upside down, the beads inside the toy coat the screen, making it look "blank" again.

EDIT: Funny how you marked it technology.