Have to admire Ken for cutting the Gordian Knot on this one, (or making another? )
I'm still umming and errring over what and why to teach it, rather than how. The thing that seems to be true, is that once you have good individual skills, the rest come easy.

Testing skill and knowledge is not that hard. Working out why he/she needs to be able to do it, - and the accrued benefit is another.