I found this interesting post on making your receivers better by focusing on a smaller target, like a tennis ball. The best part is drill like this is also fun, so they kids get better while having a good time.
How Tennis Balls Help Make Drastic Improvements with Receivers : Football Drills & Plays
This is one of the receiver drills the players and I enjoy doing often. This drill is a fantastic way to improve hand eye coordination and will improve reaction time.
Receiver Drill Using Tennis Balls
For the receivers:
I have half of my receivers line up about 7-10 feet away from a wall, facing a wall. (Spread players out several feet)
Then I have the other half stand behind them with a tennis ball.
The drill starts by me telling the guys catching the ball, which hand to catch with, (alternating between right,left and both)
Then the player with the tennis ball throws the ball against the wall, and the object is to have the playing facing the wall catch the ball.(without knowing where the ball will be thrown)
For the more advance, you can adjust this drill by:
A. Having the players lie face down on the ground, then jump up as ball is thrown.
B. Have the players run in place (facing the thrower) then as ball is throw, players turn to catch ball.
This is a simple drill, however I have seen drastic improvements with receivers, after implementing this drill in practice.
So if you have the time why not give this a try?