This is your most basic of all youth basketball lay-up drills.
Form two lines, one on the right side, and one on the left.
Player in Line 1 dribbles hard to the basket, shoots lay-up, then goes to the back of Line 2.
Each player in Line 2 moves in to get the rebound when it is their turn, then goes to the back of Line 1.
If it is possible it is better if every player in Line 1 has a ball. If not, players in Line 2 can pass ball to the next player up at the front of Line 1.