The young player stands at the baseline, ready position. The coach holds 7 balls in his hands; the basket of balls is close to the net (same side);
Have the kid set (turn sideways, racquet cocked), then drop a ball in front of her; she hits it and follows through; then make a step toward the net and drop another ball, and so on until she hits the seventh ball closer to the net.
The kid will hit every ball that you drop in front of her moving closer to the net.
Once she hits all the balls, take another 7 balls from the basket and repeat the tennis drill, this time moving away from the net – hitting and stepping back.

Note: Good tennis drill to teach moving into the ball, proper preparation, footwork, and balance for little players.