My Second Favorite Baseball Hitting Drill
Getting the barrel out into the zone early on is extremely important. The above drill is great for teaching kids how to do it without making them think too much and ending up with a clunky, machine-like swing. I love drills that get the player to figure it out on there own, and that's what this one does.
If you're coaching players, just give them the rules of the drill - the ball has to be moved back toward the catcher about ten inches - then they have to hit the ball up the middle. Try to get them to hit the ball as hard as they can and consistently hit line drives up the middle. The tendency will be to hit the ball toward the opposite field. Again, stress to them that the goal is to hit the ball up the middle.
Try to resist the urge to coach them on how to do it and just let them figure it out on their own. Once they do, let them know that the feeling that they just created is a better swing for them and to try to take this feeling into a game. It's a swing feeling that will work great for increasing their consistency and power.