I was taught in the instructor pilots course that students can only process about 8 words when at the controls. It isn't difficult to condense things down to that. Sometimes, you have to form the complex instructions to an 8 word question. Wait for the student to respond, and then give him another short burst...if he can handle it. Timing counts.

Another concept is the building block method where you teach from the known to the unknown (simple to complex), to build upon the knowledge base until you have taught it all. When you break things down, they are really just a series of maneuvers. For example, downwind is straight and level flight at a certain airspeed. Turning base is a turning maneuver that sometimes becomes a descending, decelerating maneuver. Etc, etc, etc.