Without saying your age, what's something from your childhood that a younger person wouldn't understand?

[pedant]Spirit duplicator – aka Ditto.[/p]

The faintly sweet aroma of pages fresh off the duplicator was a feature of school life in the spirit-duplicator era.[4]

Mimeographs, instead of using solvent to transfer the colored wax onto the copy uses a stencil through which honest-to-goodness (if a little weird) ink is forced onto the copy.

A 30-copy classroom assignment is going to be Ditto. The several hundred-copy school newspaper is Mimeographed.