Diagram 1: Players 1 and 2 are guards. Players 3 and 4 are rebounders. Players X1, X2, and X3 are defensive players (you can use 1, 2, or 3 defensive players). I suggest starting with one early in the year and progressing to three.
Diagram 2: Player 3 has the basketball, and puts it up against the backboard so that it comes off to 4. Player 1 and 2 move to the outside for outlet pass. Player 4 passes to 2 who pass to 1 in the middle. Player 1 takes the middle on the fast break, 2 and 3 fill the lanes and 4 becomes the trailer. X1, X2, and X3 play defence. They can challenge the rebounder, challenge the outlet pass, challenge the ball in the midcourt area or drop back toward the basket. They have the choice of what they want to do. They should mix it up so that the offence can recognize the defensive situation and adjust to it.

Practice the fast break against 1, 2 and 3 defensive men.

The rebounder can put the ball up against the backboard so that it comes off on his side or to the opposite side. If you designate the middle man (we do and he is 1), the outlet pass comes out to him, he takes the middle. If the outlet pass comes out to the other guard (as in diagram 2) then he passes to middle man.