Carefully edited out my "probably"? I disagree with your empirical claim. In my experience,most shadowing is done to (a) irritate the keeper and (b) make it harder for him to get to the ball. (And perhaps (c) for no reason the player understands except that the coach told him to.) But I agree that attempting to block vision while in an onside position is legal so long as it does not also impede the movement of the GK. On a CK, that is virtually impossible, as the GK will be moving toward the ball so trying to block his ability to see the ball after it is kicked will generally impede his movement.
Agreed. At middle school ages, there can be a huge discrepancy in size. I've seen coaches have a large player position themselves in front of the keeper and then have him pull out the moment the ball is kicked. I see nothing wrong with that. It certainly won't be as effective as kids get older.
What I see happen most times is an attacking player marks up the keeper. The keeper then summons an assistant who's job is the start shoving the attacking player out of the way. Either that or the keeper the moment the ball is kicked shoves the defending player just enough to create space. I hate to call a play dead for either offense and certainly hate to give a soft PK because someone is being an ass to the keeper, so I tend to stop play and speak to both if I see it happening to let them know I'm watching.
The point of my conversation is so the keeper and his defender don't do something stupid and force a PK. And the attacker is on warning that I'm watching so when I call it against him, he has no excuse.
Thanks, this is very helpful for something that I've struggled with for some time, when questioning whether the keeper has any special considerations in such cases.