Set up cones for the players to run through that make a running pattern that can be used during flag football games (you can also have the children help you come up with ideas so they understand the running paths better).  Add cones to mark the zone the quarterback must stay in when throwing.  Have the quarterback stand within this zone and throw to each player as they complete the zig-zag run.  Alternate quarterbacks if your team has more than one.  You can also have the player at the end of the line play defense on the quarterback to add more intensity and create a game-like atmosphere during the flag drill.