One technique coaches might try during practice is to place one or two cones on the first base line. Make sure they are spread out. When the player hits the baseball off the tee and runs down the line, he must carry his bat and drop it either near the one cone or between the two cones.
Coaches can also place a baseball glove where the batter should lay down the bat. Some teams will put a parent halfway between home and first and the player will have to hand the bat to the parent as he runs down to first. Whether it is a cone, a glove, or a parent, coaches should be prepared that this is a regular issue when it comes to t‒ball. This is also an issue in the older leagues, which is why it is imperative for coaches to try solving the problem at a young age. Having a prop or person will condition the players to be aware to do something with the bat after the hit. Coaches can remove the cone, glove, or parent during the season if the team doesn’t throw the bat.
This drill is from Marty Schupak's best selling book: