When you ask your dd5 the items that are on the grocery list (because you forgot the list) & she can list them in order.

When your ds8 keeps an "idea notebook" of new engineering designs and you are pretty sure some of them could be feasible.

When you have to declare a "question free zone" for the 10 minutes it takes to get everyone out the door for school.

When your kids ask for a separate library card so they can check out more books.