This is an excerpt from Coaching Youth Baseball by Babe Ruth League & Inc..
FIGURE 8.9 Fielding ground balls drill.
Put one player at second base and one at first base as shown in figure 8.9. (You can have a second player at each base so that players can take turns receiving throws.) Divide the rest of your players into two single-file lines, one at the third-base position and one at the second-base position. Two coaches should be in the middle of the infield with a bucket of balls. The coaches will roll or hit ground balls to the first player in each line, who will field the ball, make a throw, and then go to the back of the line. The fielder at third base will throw to the receiver on second base, while the fielder at the second base position will throw to first base. The coaches should call out commands as the fielder fields the ball. For example, for a right-hander, these commands could be “right-left-field, right-left-throw.” Coaches should watch to make sure that players drop down using proper technique, center the ball, funnel it, and then skip and throw. For younger players, we recommend that coaches roll the balls underhand. For older players, only one line should be set up at the shortstop position so that longer throws are made to first base. In addition, this is also a good drill for measuring the arm strength of your players. Balls can also be hit or thrown to the forehand and backhand sides.