Keep it short, slow and comparative. Say what you are changing in a sentence or two, then show the unwanted result and the desired result one after the other, slowly enough that the student can see the difference. A fast demonstration, or one that shows only the good cast, asks the student to notice a change from a starting point they never saw.

The six-step method recommends slow demonstrations, and exaggeration where it helps. Exaggeration is a teaching device, not the target: make the fault bigger so the contrast shows, make the desired movement bigger too, and bring both back to normal size once the student is copying the right one. An exaggerated model left in place is a new fault.

Put the contrast where the correction acts — the wrist, the stop, the tip path. Point at it, show it, then hand over the rod and watch the student try it. A demonstration is clear only if the student can do something different afterwards.

Source

From Bruce Richards’ six-step fault analysis and correction; the exam uses it in Task 19; terms follow the FFI Fly Casting Definitions.