Tell them stories.

“Argue with anything else, but don't argue with your own nature.”

“Must is not the same as can, Lyra'. 'But if you must and you can, then there's …”

“You going to be a scientist when you grow up?” That sort of question deserved a…”

“No,' he said, 'memory's a poor thing to have. It's your own real hair and mouth…”