The title is a little grandiose, but this isn't going to be a post with a strict plan or loads of cited research. I'm going to forego the background of explaining the assumptions, so anyone who is curious about the scientific evidence behind these statements will have some extra reading to do elsewhere.
First and foremost, you absolutely do not need to worry too much about the arm action of a 6U athlete.
6-year-olds typically find 3-pound weights to be quite heavy, so obsessing over a child's shot-put throwing style, for example, is an exercise in frustration. Patience is going to be your friend because trying to correct a "bad" arm action with mechanical cues and excessive or unhelpful feedback simply won't work.
Put yourself in the mindset of a young athlete. Some guy is telling you that your arm needs to here and do this. You are trying. It is not working. Occasionally, he says, "Great job!" Occasionally, he says, "No, like this." You don't understand the difference. To you, it looks and feels the same. Great, now he's saying, "Reach back!" and "Finish!". You're pretty sure you did both.
There are three common paths out of there:
- You luck into a good enough arm action that the coach shuts up.
- You get frustrated and eventually tune out the coach.
- You focus on your arm being there and doing that instead of just throwing the ball.
The most unlikely scenario? The kid executes and repeats the internal mechanical cues perfectly and instantly has a prettier arm action.
Is that prettier arm action the path to future success, though, or is the kid now too focused on arm action instead of throwing? Did you just put a restrictor plate in that kid's engine?
In other words: even if it works, did it really work?
The most important thing you can do is keep it fun because that's the real purpose of the game.
So now you've promised yourself that you won't nitpick arm actions or teach "mechanics" to smaller kids, but now what? How can you help them develop without the risk of doing more harm than good?
The real answer here is that you can leave the 6-year-old alone to play the game. As kids grow and develop, a lot of early athletic development issues, like a wonky arm action, work themselves out naturally. There's some survivor bias in that statement, since the kids that don't work it out don't tend to keep playing, so what can you actually do to nudge things in the right direction?
Keep the cues simple:
- Throw it hard.
- Throw it where you want it to go.
Create micro-games like target and distance challenges. These can range from gamified catch, to landing throws in buckets, to measured long-toss. Sometimes simply playing catch at the right distance is enough.
The last bit of advice I have to share here is to be careful not to make micro-games too competitive. No one wants to finish last all the time, and the wrong kind of competition could drive a kid away before they have a chance to develop. Sometimes kids need to compete with each other, but the real competition should be focused on improving scores/results over time.
Keep it short. Keep it simple. Keep it fun.