I usually start in the first lesson by demonstrating a turn without rudder and a turn without ailerons.The student will notice it "feels funny" and looks odd.. .I then do it again but have them look at the ball and the nose of the aircraft.. .Then demonstate a couple of coordinated turns to show the difference.I let them fly for about 30min using only the rudder..... .Shows how to use your feet and trim correctly.. .I then say "right rudder" about a 1000times till they get their PPL.Some get it quicker than others.