It's less directed self-study as tutoring and mentorship. My experience is a bit different; the trick is to: 1) first expose kids to the general concepts 2)

It's less directed self-study as tutoring and mentorship. My experience is a bit different; the trick is to: 1) first expose kids to the general concepts 2) build them out in as broad a range of contexts as possible, slowly and gradually. Write some code. Do some engineering problems. Etc. 3) Go back and formalize it once the intuition is there The earlier you start, the better. But you want a different calculus book for a college student, as for a high school student, as for a middle school student, as for an elementary school student. The earlier you go, the more you want pictures and intuition (and the more time you then have to build out the formalism later).