Train the first touch that creates a shooting position and the strike that follows it, from around twelve metres. With no combination to manage, a coach can watch the two touches and correct them on every repetition.
Set one mannequin about twelve metres from goal, a server deep and to one side, and a keeper in goal. The server feeds into the finisher, who takes one touch to set the ball away from the mannequin and strikes with the second. Alternate the side the serve comes from so the finisher receives on both feet. Rotate the server and finisher every couple of minutes, and keep the finishing distance honest.
There is a case for keeping one genuinely simple finishing exercise in any coach's collection. Elaborate patterns are more engaging and produce better sessions once the technique is there, but they also hide it: when a player misses at the end of a five pass move, it is rarely obvious whether the problem was the strike, the touch before it, or the pass before that.
This removes every one of those variables. A serve, a touch, a shot. If the finish is poor, the cause is visible immediately and can be corrected on the next ball rather than three sequences later.
The first touch is almost always the culprit and almost never the thing players think about. A touch that stops the ball dead leaves a player standing over it with a mannequin beside him and a keeper set; a touch that pushes it across the body into open space produces a straightforward strike from the same starting position. Same serve, same distance, entirely different chance, and the difference happened before anyone thought about shooting.
Twelve metres is close enough that placement beats power comfortably. Players at this age default to hitting it as hard as they can, which at that range is a comfortable save. Asking for a side of the goal rather than a hard shot changes the conversion rate immediately and is one of the easier habits to build early.
Alternating the serving side is the detail that stops it becoming one-footed. Left alone, a finisher will shift every ball onto his stronger foot, and the drill will have produced a hundred repetitions of half his game.
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.