Move It! comes in two variations. One is to learn to move your opponent from side to side. The other is to move them deep to short. You will need two different colored spots.
Side to Side
|Dust off your spots - you will need them|
for this drill
Deep to Short
Same idea, but now one spot is placed in front of service line and the other behind the service line. Player must call out the color of the spot or 'short'/'deep' before each shot and make it happen. This will be a workout for the returning player, as both will still be expected to recover to center baseline after every shot.
Give each players either 10 balls and switch, or switch after a set time limit so that each player has a turn at directing the ball.
For your young beginners, instead of rallying, have them tossing and catching with foam or red balls on the 36-foot court.
Adapted from USTA's QuickStart Tennis guide