Limit the amount of time you spend teaching (more teaching does not = more learning)....Take Home Point: teach a quick pearl about a case and move on. Dont belabor the point and keep teaching for 5-10 minutes. You will loose the learner.
Make teaching points applicable to the patient. Theoretical stuff is fine but no one cares about the Krebs cycle or ATP.
Teach "on the fly" (teach as good teaching moments come up on each case). "Board talks" are nice but are often times not practical in a busy ED.
Above all, be enthusiastic...without this all teaching will be ineffective