This is as simple of a rebounding drill as you can have. It is designed for those teams who are having much trouble rebounding and it seems as if there are always more men on the other team going for the boards.
Get the team into a five on five half court setting and the coach has the ball. Two extra offensive men should be standing about 8 feet behind the three point line (near the hash marks on each side). Coach passes the ball in and the offensive swings it a few times, making the defensive team play defense (as if they were in a game). When the coach receives the ball back and shoots it, all seven offensive players (including the two who are standing 8 ft. out) crash the boards relentlessly. Once the defense clears three boards, switch things up.
7 on 5 (12 players) or 6 on 4 (10 players)
Make sure the players realize that they must go out and find someone to box out quickly and hold them there. Sometimes it is possible to box out two men and that surely needs to happen in this drill. This is designed to simulate a game situation, so make sure your players create the first contact and that they hold the defense out as far as possible. An ideal box out for a team would be to have the defense holding their men back so perfectly that the lane is clear and a ball could actually bounce in the key before it is rebounded. That is obviously unrealistic, but it should be the ultimate goal.
The defense might have to clear four or five rebounds before they can come off.
You could send only one extra offensive man to the hoop.
Finding a man to box out
This basketball drill is licensed under a Creative Commons License. This drill is from Pål Degerstrøm at www.degerstrom.com/basketball.