It can help to practice tipping the bike, they'll see it is easy to stop your fall by putting your foot out. Have Your son or daughter wear long pants, a helmet, elbow, wrist and knee pads (the more protected you are, the less you fear falling). Practice in a big empty parking lot, a church paking lot is usually empty during the week. It's much easier if you don't have to worry about running into anything. Don't look down! Keep your eyes where you want to go-- forward. Practice for one hour, five days in a row.
That's what has worked for us.