My math teacher in high school had one of these, though he never mentioned what it was to us. I used to stare at it off and on during class, and eventually it clicked “Oh, it’s a clock!” After that, with some intense staring, I figured out the pattern and was satisfied. Asked the teacher about it later, and apparently I had taught myself binary.

That knowledge displaced whatever he was talking about that day. Hopefully it wasn’t too important.