And, to answer you didn't know to ask, I have almost exclusively taught 19 yr olds and up. I am currently an RN, and although most of the teaching we do is in small-scale settings to either patients and families or inservice type setting with other nurses, as part of the BSN (or at least in the BSN program I took) you also take a dedicated teaching course, and spend a lot of time learning to create lesson plans, creating them, and then teaching from them. The 45 minute or so lesson I taught last week to a phlebotomy class was on the pathophysiology of the heart, along with a brief recap of anatomy and physiology of same.
I've seen a lot of good teachers and a lot of bad teachers in the course of racking up six college degrees as well, and the good ones always spent a lot of time outside of the classroom in preparation. My own father taught for 3 decades, and I recall all too well that he went in 3 hours before the students did to prepare for the day, as well as often working some in the evenings.
As to common core, I've been watching it closely, but from the outside. The overall notion is a good one - a common set of standards that all students should be able to meet at various levels. The implementation, sadly, seems more to be about finding ways to siphon off public funds for private 'curriculum development' enterprises that are weaving conservative ideology into lessons. I don't believe administrators who are not, nor have been teachers, are best suited to evaluate teachers. Teachers are best evaluated through peer review.