The explanation succeeds when someone can use it without borrowing your confidence along with it.

A good explanation can leave two different things behind. One is belief, which runs on your authority and lasts only as long as you are in the room. The other is understanding, which the person can carry into a new situation and use without checking with you first. Explanations that impress tend to produce the first, because the listener is following your certainty rather than the reasoning.

After explaining something, ask the person to apply it to a case you have not covered. If they can, it landed; if they can only repeat what you said, go back and give them the part of the reasoning you skipped.