Tonight with your 13 to 17 year old
The prompt
“Where's the line for you between something being private and something being a secret?”
What to listen for
If they draw a clear distinction, private is "mine to share when I choose," secret is "something hidden because it's wrong or scary", that's a strong sign of healthy judgment forming, and it means they likely feel they can come to you with real problems even while keeping normal things to themselves.
If they get defensive or say "why does it matter," that often means they feel like their privacy has been questioned or invaded before, and the question itself is landing as suspicion rather than curiosity, soften and reassure that you're not asking about anything specific.
If they think out loud and land somewhere uncertain, that's actually great, it means they're wrestling with it honestly rather than reciting an answer.
What this tells you
This tells you how much they trust that their independence will be respected, and how much they feel their choices are genuinely their own to make.