Teaching difficult concepts

After my employee made a mistake today (caught early enough that I could correct it without hours of rework), I got to thinking "what's the best way to train/teach a difficult concept". Normally I use over exaggerated examples to show how to do the work properly, while asking why, or what the result might be, the outcome is the way it is.

Due to there being more than one way to skin a cat, I figured that maybe there are better methods to teach. Anyone got some more teaching methods?