Working Together as a Referee Team:
In matches where Assistant Referees are used, the two ARs and the center Referee work together as the third team on the field. The main tools of communication among this team are proper use of flag signals, eye contact, and good positioning. Here are some pointers (not intended to be a complete list) on how to have successful teamwork among the Referee and the ARs:
Assistant Referees:
Must know the offside rules (Law 11) and the flag signals for all of the restarts and for indicating substitutions
For a corner kick, your flag should always point to the near corner, even if the kick will be from the other corner - otherwise it is hard for the Referee to distinguish from goal kick signal
For substitutions, AR on the team side usually signals first, but AR on the other side should mirror the signal if the Referee doesn't see it
Must keep the proper position - generally that is in your half of the field and even with the second to last defender of the team defending that end of the field (or the ball if that is closer to the goal line than the second to last defender
During active play, as you adjust your position, as much as possible use side to side movement, but when you need to sprint, hold the flag on the field side of your body - two reasons for this: easier for the Referee to see it, and you won't trip over it
If you see an offside infraction or a foul prior to the ball going into the goal, raise your flag and signal, and make eye contact with the Referee
If the referee does not make eye contact and doesn't see your flag, lower the flag but continue to attempt eye contact prior to the kickoff
If the goal is a good goal, make eye contact with the Referee and then run up the touch line toward the halfway line
Remember that your positioning is dynamic during play. Stay even with the second to last defender or the ball, whichever is closest to the goal. Please don't snap your flag unless you need to get the Referee's attention and the Referee is not responding to eye contact. Review the signalling diagrams in Law 6. Also, you should run your watch (count-up, NEVER count-down) and keep track of the score as if you were the Referee. Two reasons for this: (1) it is helpful to the Referee to have this backup and (2) if the Referee is injured you may have to step in as Referee.
Mirror Signals:
ARs should use their judgment in mirroring the signal of the Referee and the other AR. The most important signals to mirror are offside (especially if the Referee has her back to the AR in the other half of the field) and substitution.
Flags:
Assistant Referees often have to sprint to keep even with the offside line during dynamic play. Please hold the flag in your field side hand when doing that. It is easier for the Referee to see the flag if it is on your field side, AND you are less likely to trip over the flag. In the usual set up, this means that if you are running toward the goal line, the flag is in your left hand, and if you are running upfield toward the halfway line, the flag is in your right hand.