With 4-year-olds, the greatest challenge is getting everyone to pay attention and not horse around. I have found that you have to constantly interact with the players to accomplish this, and lines do not help.
 Coaching T-Ball
How to Keep Their Attention
One thing that has really begun working for me is throughout practice, and during drills, to yell out “<Team Name> Ready!?”.

I have taught the team to jump into their “Ready Positions”, find and look at the ball, then yell back “READY!”.

This helps keep/get their attention during practice as well as in games.   I have started making somewhat of a mini-game out of it by throwing the ball to the player who had the quickest reaction, and letting them go first in a drill or letting them pick a fun drill or game.

I have even had a few other coaches tell me after games that they could tell it grabbed everyone’s attention (even the crowd’s) and that it was somewhat intimidating, especially when the team was in unison.   Give it a try!   It works and is fun for the kids.