A good example makes the next unfamiliar problem less lonely.

Meeting an unfamiliar problem, a fair share of the difficulty is the suspicion that you are the only person who has ever found it hard. A worked example does two jobs: it shows a route through, and it proves somebody else once stood exactly where you are standing. The second is often what keeps a person in the chair. Isolation turns ordinary difficulty into evidence of unsuitability.

When you explain something, show one complete example including the part where it goes wrong. Say what confused you the first time. That admission is frequently the most useful line in the whole explanation.