Tonight with your 5 to 8 year old
The prompt
“Can you think of a time keeping a secret was the right thing to do, and a time it wasn't?”
What to listen for
If they land on "a secret is okay if it's a surprise, but not okay if someone is getting hurt," they already have a real, workable sense of the difference, a great foundation to praise and reinforce.
If they struggle to separate the two, or say all secrets are fine (or none are), this is a good, low-stakes moment to gently walk through the difference, surprises have an end date and make people happy; secrets that protect someone from a hurt should always be told to a trusted grown-up.
If they mention a specific secret they're currently holding, stay calm and curious rather than alarmed, thank them for bringing it up and ask a few more gentle questions.
What this tells you
This reveals whether they can already tell the difference between a fun surprise and something that needs a trusted adult, which matters for keeping them safe.