Originally Posted by 22B
For comparison, the K12Inc Prealgebra course simply stated formulas (after adequately defining n!)
P(n,r)=n!/(n-r)!
C(n,r)=n!/[(n-r)!r!]
without any explanation of why LHS=RHS. (Usually they give some kind of explanation for things, but not this time.) Then they have some "worked examples" which are easily skipped past, then a routine quiz.


Pardon me, but this is just awful.

(OT: Judging just from the excerpt above, you'd be much better with at least EPGY than with k12.com. EPGY does not use so-called discovery method as much as AOPS, but at least EPGY would never just give a formula to use (and memorise), without deducing it.)