Teach the kids all the safety rules and hand signals for bicycling before they are allowed on a bicycle. They should know the hand signals for right and left turns and a full stop. Then have them demonstrate the signals and answer questions about safety.
Plan your route. Even if you are not sure how far your group will bike or exactly where, plan a tentative route. Remind kids they are to stay behind you (in single file if on roads) at all times and not ride up ahead.
Tell the kids to put on their safety gear. Make sure bicycle helmets and protective padding are securely strapped on. Tie all shoelaces and don't let them hang. Pant legs should be close-fitting so they don’t get caught in the chain or on a pedal.
Fill and attach water bottles on the bikes for each child. Check the tire pressure and properly inflate if needed. Test the brakes, and tighten nuts and bolts.
Begin biking -- adults should be in the lead with children following behind -- this helps prevent a child from biking too far ahead and into traffic. If your group has several adults, one or two can follow behind the kids to make sure no one strays off to the side.
Let the kids practice hand signals, following your lead, at each intersection. This applies to country roads and parks as well, at each turn in the path or fork in the road.