Here is a new student of mine. This video is at the end of his 4th lesson with me.
He just turned 8 a week ago, and the bat he is swinging is 29 inch, 23 ounce (-7). He is hitting 50mph pitches from an Iron Mike.
When he came to me, he had huge lunging and balance problems, a lot of head movement and bathead casting. He still has work to do of course, but these are pretty good swings for an 8 year-old and he is learning quickly. I've been working on getting him to use his body and he's starting to get it. Not many 8 year-olds can swing a 29, -7 this well. This bat is probably a little too heavy for him, but it proves my belief that kids can swing heavier bats if they learn to swing correctly.
I have my list of things he needs to fix, but I would like to hear what others see;
BTW, he absolutely crushed the ball on the second swing in this video.