For levels and leagues where players can lead off when the ball crosses the plate, run an exercise requiring a pitcher, a catcher and a first baseman and one baserunner with batting helmet (at first base).
The remaining players line up in foul territory to take their turn running. To begin, the pitcher pitches to the catcher and the catcher makes a throw to first base to try to catch the baserunner coming off of the bag to go to second base.
The object is for the baserunner to get as far as possible toward second base (but not to go to second) and then try to get safely back to first before the throw. Mark a line in the dirt at the farthest distance that each player gets to if they get back to first safely. That tells the player how far they can get off the bag and still get back during a regular game. We have a competition to see who can get the farthest.