For me (learning not teaching) my Sensei normally demonstrates at speed with a high ranking member, then slowly whilst explaining each section.
From there newbies are paired off with higher ranking members (we have a good ration of about 20% newbies and the rest are mostly dan of some sort)
Sensei then walks around and watches each person, and stops us and explains and demonstrates on a one on one level where needed.
Of all the marital arts i have done this seems the best teaching method (also you develop a good relationship with Sensai very quickly
)