Everything a children's app should refuse to do, refused.
A child never creates an account, never types into an open text box, never sees an ad or a leaderboard. Adult-created accounts, QR class-card login, and moderation on everything, the safety architecture in plain language.
Never an open-web sign-up by a child.
Nothing to remember, nothing to mistype.
Nothing profiled beyond learning.
A child is never ranked against another.
A child can't type into the open.
Nothing about a child is hidden from their adults.