Attack the wide duel and finish it with a low ball. Run at the defender rather than passing sideways, beat him on the outside, get to the byline before releasing, and pull it back behind the last defender for a runner arriving.
Mark a wide channel about 34x26m running into a goal, with a marker on the byline. A winger starts with the ball in the channel, a full-back defends, a striker starts central and slightly behind, and a keeper defends the goal. The winger must beat the defender and reach the byline marker before releasing the ball, and the delivery must be along the ground. The striker times his run so he arrives as the ball does, not before. Swap the roles every two repetitions and work both flanks so the weaker foot gets used. If the winger cannot get past, playing back and going again is a perfectly good outcome.
Wide play is one of the first team ideas coaches try to teach young players, and it usually arrives in the wrong form. The picture in the coach's head comes from the weekend's televised football: a winger whips a ball to the back post and somebody attacks it in the air.
Two things make that unusable at this age. The first is physical. A useful lofted cross needs striking power a nine-year-old generally does not have, so the ball either falls short or balloons over everything. The second is a rule. Deliberate heading is an offence at under-11 and below, which means an aerial delivery has no legal target even when it arrives perfectly.
So the aerial cross is not a skill to be taught early and badly. It is simply the wrong tool for this age group, and the right one is the low ball pulled back from the byline.
That changes what the practice is about. The delivery stops being the hard part and the duel becomes the hard part, which happens to match what this age is supposed to be doing anyway: running at defenders, backing yourself, beating somebody one against one.
Getting to the byline is the detail worth insisting on. Young wingers release the ball the instant they are past their man, from a position where the keeper can gather it and the defenders are all facing the ball. Two more seconds of carrying changes the geometry completely, because from the byline the pull-back arrives behind everybody, with defenders running toward their own goal and the striker running onto it.
Where the ball goes matters as much as when. Across the face of goal is a pass to the goalkeeper. Behind the last defender, into the space he has just run out of, is a chance.
And the runner needs coaching too, because the instinctive move is to sprint to the near post and arrive early, which turns a good delivery into a scramble. Arriving as the ball arrives is a timing skill, and it is worth practising deliberately rather than hoping it appears.
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.