For a stretch to become effective one part of the body must be anchored (unmoving), whilst another part moves away from the anchor. When we create a stable point by instructing what is anchored and what is moved, students develop sensitivity. Working with this exercise increases the trainees’ skill of teaching poise.
Examples: In tadasana, press heels as you firm the thighs to lift chest. In vriksasana, press into the standing L foot. Without disturbing the inner L heel, bend and raise the R foot to the L inner thigh.
With a small group of students teach an asana and define an anchor, what is moved, and observe the expression of stability in the students.