A good T’ai Chi Chih teacher must be able to detect the faults of the student – and then be able to correct them. This means that, through his or her own practice, the teacher must have come to more than a shallow understanding of T’ai Chi Chih movements. Teaching is more than just showing where to place the hands and feet.
Once the teacher has shown the correct way to move (softly, with continuity), he or she might look for faults in balance. In a movement such as “Pulling Taffy,” the pupil may have shifted the weight to the left side while the hands are still on the right side. (The hands and weight must shift together to the Yang side.) This is awkward. As in all movements, the shift in body weight must be synchronized with the movement of the hands. Teachers must have an understanding of “substantial” and “insubstantial.”
If the pupil does not have enough body coordination to do this, then he or she must be allowed to do the best he or she can. However, a teacher must be able to do this gradual shift of weight correctly. The pupil will imitate what and how the movement is done by the teacher.
With most it is a lack of understanding, and the teacher must be able to spot the difficulty and correct it through example.
Another common difficulty is moving forward to a stiff front knee, instead of a bent knee that takes the weight and becomes substantial. This can also happen in regard to the back knee. The back knee should bend the same amount as the front knee, not one bending and the other becoming stiff (and remaining insubstantial).