|I'll take the slice on the deuce side please|
Divide the courts into halves. Singles play is confined to those halves. First player to 11 points wins.
Divide court in half front to back.
Divide court in half deuce/ad.
Divide court in half diagonally.
Note this simple drill can easily consume an entire teaching hour or more if you play first to 11, best 2 of 3 for each variation. Or, develop a series of lessons progressing from each 'slash' or division of the court. IMO the way they are listed above is also the progression of easiest to hardest.