With all of our teaching we do three things, explain what we are doing, demonstrate it apart from the student, demonstrate it on the student, and eventually have them demonstrate it on us. This engages the three main types of learners.
With stances I generally will describe the purpose of the stance, the alignment of the feet, hips, and upper body, and weight distribution of the feet.
I'll have the student move into a stance from another several times and correct the stance each time so the person gets the feel of an incorrect and correct stance and typical errors that they are prone to.
Pretty similar, purpose of the basic block, correct movement of the arm, alignment of arm to the body. Then feed several attacks to lock the motion in.
Whenever I teach I will comeback and revisit a topic several times in a training period or private lesson. So I'll teach one block, go on the next one, come back review the first block, review the second, teach the third, etc. This forces a student to "reload" the information several times in a single lesson and that tends to lead to better retention versus "block" learning where you do lots of rote motions as a group then move on to the next learning example. (I based this off of a couple of studies on how people learn, it seems to work fairly well in practice.)
Once a student has gotten an appropriate group of basics together I'll put have them run through a drill or set to get the feel of basics isolated in action. This might be "star block set" or a simple footwork isolation drill. These aren't required sets/forms, they are just drills we use to get the basics practiced.
Lamont