I think you two agree (as do I). So much of this thread is focused on stuff like interest, but spending less than you earn and knowing how to calculate risk over time are massively more general and useful skills to learn.

I'd keep it at basic inequalities like "does that cost more than what I have?" Tracking continuous-time risk is more a college thing.

Unclear whether we're in violent agreement. Parenting is all about evoking interests whilst suppressing urges. Since money is a means of both its importance comes out in the wash, so to speak.