Originally Posted by 22B
Another question, what's your approach to assessing "mathematical maturity" and readiness for certain mathematical activities?
Pre/post-tests (online) for AOPS books and courses would be useful for this.

Originally Posted by 22B
For example, I haven't mentioned at all to DS7 about theorems and proofs, since he's not ready for that. He can understand and explain things, but I'm just happy for him to think about things without worrying about rigor at this time. Know what I mean? What other stages of "mathematical maturity" should I be thinking about?

AOPS "Prealgebra" book asks students to construct proofs (AFAIR, distributive property, etc.) at the very beginning.