@Ben Mensen I also have a 9 year old. We started with open 45 degrees to focus on coil and weight over the rear leg. We did regular swings off the tee and soft toss. The tee was placed deep, about middle of the body, and soft toss to the back hip to keep his weight back and not lunge or push his hands. We recently started flamingo drill with pause before swinging and one leg swings because he has a tendency to speed up his load and shift his weight during front toss/BP/games. We sonetimes over exaggerate the tilt and think about hitting a fly ball to first base because He tends to get rotational with his upper body and hit ground balls the left side. Of course this all depends on you son's swing but wanted to share some of the drill I have been using. Be patient and remember he's only 9. He will likely revert to his old swing during games in the beginning. I have been working with my son for about a month and this past weekend is the first time he started catching barrels and driving the ball

I saw someone mention tater foam balls but driveline and Marv have machine foam balls. They seem to be 3-3.5 oz. I'll stick with smush balls for now. Excited to see the new products.