“What is one thing you have learned from me — not the big life lesson, the small, specific one — that you still use or think about?”

The question sits across the top; you each answer on your own page. Whoever writes second reads the first answer before writing — agree, argue, or correct the record.

Why this question

A phrase I used, a way I handled something, a standard I held that rubbed off.

And once you’ve both answered

Have I ever told you what I learned from you in return?

Answering it honestly

Whoever writes second reads the first answer before writing — properly, not a skim. Your page can agree, argue, or correct the record.
Be specific. Dates, places, what was playing, who else was there. Wrong details are welcome; they're evidence.
Don't negotiate a joint version. Two accounts that refuse to match are worth more than one polished one.

And the house rule, whatever the mode: leave a blank rather than write a lie. A blank can be filled later; a lie sits in the archive forever, and you both have to live with the paperwork.