According to the flight instructor, the pilot receiving instruction was seated in the left seat and manipulating the flight controls during takeoff. As the airplane rotated and became airborne, it yawed left. The instructor intervened and aborted the takeoff. Before the airplane landed, the left wing impacted the airport windsock located on the north side of the runway. The airplane sustained substantial damage to the leading edge of the left wing. The instructor reported no mechanical malfunctions that would have precluded normal operation.