This is done not so much to teach you how to turn the airplane (since there is much more finesse involved when you do it for real), but to give you the feel of the airplane.
Also, during your first time up in the air with the instructor, you may be asked to do a small turn to the left or right using just the control yoke in your hand.  This is done not so much to teach you how to turn the airplane (since there is much more finesse involved when you do it for real), but to give you the feel of the airplane.  You will be seeing how the machine reacts to the wind, how the sounds change, how the feeling your hand changes the steeper the turn, and lots of other little stuff that’s fascinating and easy to absorb pretty quickly.