The best advice I ever saw on teaching anyone to ride a bike was to remove the pedals, lower the seat and let them scoot along on level ground for 10 - 20 minutes. Get them to lift their feet off the ground and their natural sense of balance will do the rest.
Stick the pedals back on give them another 10 -20 minutes of scooting and putting their feet on the pedals. They won't be as worried about balance at this stage and can probably start to pedal.
Once they have done a few small circuits, show them the rules of the road.
tags; How to ride a bicycle
First time on a bike
Davantine Buvvha
September 2011