Corner kicks are a very important for both teams. For one, there can be as many as 22 players, yes, including the opposing GK in the penalty area which if you recall from your entry level class is 44 yards wide and 18 yards deep.
With that said, it is very important that the referee have a good angle to view and be In the proper position.

What should the referee observe first?
The number of players and the match-ups that are happening. Usually, the tall defenders of the team taking the corner kick will move forward to gain that height for the incoming kick.
Secondly, he must observer the GK. Is that GK being defended closely? How many attackers are near the GK? You have to ask yourself, “why are there attackers near the GK?” They are there to obstruct or distract the GK of defending the kick once it is in play.
This is why an angle of view and the proper position is necessary.

Although the diagram shows a stationary position, referees must be prepared to move and have the proper angle when they players are in motion. Many times, the view of the referee is blocked due to the movement of the players, so referees also need to move to have a better angle.
In the illustration above, you can see that the GK is tightly marked. Therefore, the referee must have a position to see any illegal challenges by the attacking blue team.
In the illustration above, the referee with the X would not be in a good position as he cannot see “through” players. Referees need to “look at” players and have them all in view.

Notice the position of the Assistant Referee. That position is critical. The AR needs to be behind the kicking player, just a foot or 2 behind so as not to interfere with the kicker. What other duties does the Assistant Referee have here?

1. 1. The flight of the ball. The Assistant Referee, by being on the goal line behind the flag, can judge if the kicking team has kicked the ball out of play and judge if the ball returned to the field of play.
2. 2. The Assistant Referee also monitors the defending teams distance from the kicker. All defenders must be 10 yards form the placement of the ball. If a defender is closer than 10 yards, then it is up to the Assistant Referee to direct the defenders back so they are within the Law. (on some fields, there may be a hash mark to indicate the 10 yard distance. If not, the Assistant Referee may have to direct the defenders, so they are 10 yards from the placement of the ball).

*****PLEASE NOTE: THE DISTANCE OF THE HAS MARK IS ACTUALLY 11 YARDS FROM THE TOUCH-LINE DUE TO THE FACT THAT THE CORNER KICK ARC IS 1 YARD.****