Juniors should learn to practice like the pros do, and that means starting with a wedge, establishing contact and hitting your driver last
You can’t fix your swing flaws until you establish a repeatable golf swing that goes down the line every time so your errors are consistent and can thus be fixed
Many slicers hit the ball to the right simply because they are lined up to the right, when they go to hit the ball their mind knows the target is to the left and then subconsciously changes the swing to outside in so that the club travels towards the target causing a slice