Keep the ball and break the line. Circulate to move the two defenders, recognise when the gap opens between them, and thread a firm split pass through the middle to the opposite side.
Four outside players keep the ball around a box against two defenders in the middle. A point is scored for a split pass that goes between the two defenders to the far side. Move the ball to drag the defenders, then play the firm pass through the gap the instant it opens. Two touch on the outside. Rotate the two defenders after a set time or number of splits.
Retention is not the objective in this rondo, and saying so out loud changes how players behave within about thirty seconds. A pass between the two defenders scores a point. Keeping the ball for two minutes without one scores nothing. That single scoring rule converts a keep-away exercise into a penetration exercise, and it is the cheapest way to fix the most common possession fault in youth football.
That fault is passing for safety. Given a choice between a square pass that is certain and a forward pass that is difficult, most young players take the square one every time, and a coach shouting be brave does not change the incentive. Making the difficult pass the only one that counts does.
What the exercise then teaches is recognition rather than technique. The gap between two defenders is not permanently available. It appears when they shift together towards one side, and closes when they reset. A player watching the ball will never see it; a player watching the defenders' feet will. That is the actual coaching point and it is worth stopping the exercise to demonstrate.
The weight of the split pass has to be firm. A soft ball through a narrow lane is intercepted by a trailing leg, and it also arrives too slowly for the receiver on the far side to do anything useful with it.
The cost to acknowledge: scoring only for splits will increase turnovers considerably at first, and that is acceptable while the recognition is being built.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.