What should you -skip- or -cut- in a class?
- optional topics
  fun things that aren't very relevant or useful later
  EG, hyperbolic functions, taylor series of tan
- hard/tricky things
  ugly $\delta$-$\epsilon$ proofs
    (e.g., multiplication of continuous functions in continuous,
     chain rule, some forms of L'H\^opital's rule)
    i.e., uninsightful proofs that you're just doing b/c you're
    guilty. If the idea is actually simple/easy, you should present
    a simple/easy proof of it. If you can't, maybe it's tricky,
    and you should admit this.
  construction of the real numbers, etc.

concretely, for a calc class:
- integrability of continuous functions
  (I think a proof of why -uniformly- continuous functions
   are integrable is good -- it's very clear.
   but it's the only use of uniform continuity in intro classes,
   (er, and the main use, even later?), and proving that continuous
   functions on compact sets are uniformly continuous is -hard- in
   calc class, and -obvious- in topology class.)
- IVT: Intermediate Value Theorem
  it's very plausible, and requires constructing the real numbers to
  really prove it.
  ...but you should point out how key it is!
- boundedness/maximum principle
  again, trivial in topology class, hard in calc
- proof of taylor's theorem?
- termwise differentiation (and integration) of series
  proof is subtle and also trivial -- just mumble uniform convergence
  so it's okay
- understanding WTF is happening in implicit differentiation
  (as this requires dealing with partial derivatives and functions
   $\bR^2 \to \bR$, which takes a while)
