Just remember that to a child, one minute can seem like an eternity. So don't go overboard with it. Rewards are another method, but I would not use them indiscriminately. If you do, they become meaningless and the children will not be developing their own sense of self-discipline. In this instance the rewards are conditioning them to act a certain way and it is not allowing them to reason why they must do so, thereby developing their character.
Moderation is the key.
Guide them Encourage and praise them.