Why is indicated airspeed rather than ground speed used during the takeoff roll? My instructor asked me this question during my lesson and I couldn't come up with any answers. He asked why do I need to look at the indicated airspeed rather than ground speed when in takeoff roll or as soon as we touchdown? 

It would be great if you could give me the reference to back it up.
Because wings work on air moving past them, not ground moving below them. 

Heck, in a 35 knot headwind, the Antonov-2 could be rolling backwards at 2 knots and still take off!