Every family cook has a recipe that lives in their hands: a bowl of rice, a handful of beans, enough flour. Measure it together with a child, the next time it is cooked. One spoon or cup, three tries, keep the middle number. Then the recipe can be written down, and it will still mean the same thing next year.
How to do it
Ask the cook to make the handful the way they always do, into a clean bowl.
Your child tips it into one spoon or cup, again and again, and counts. Halves count as a half.
Do it three times. Hands are never quite the same twice.
Keep the middle number of the three. That is the handful, written down.
Use the same spoon or cup every time you cook it, or the number means something else.
What are you measuring?
Three tries, in cups:
The middle number is 2.
For the recipe card
Written down
Our cook's bowl of rice = 2 cups, measured with the same cup.
Keep the spoon or cup with the card.
The same idea is a children's story on Spark & Anvil, The Same Stick: two teams build one drain, and a boy copies one stick so both halves meet.