THE GLIDER INSTRUCTOR (CFI) REPORTED THAT AS THE GLIDER WAS BEING TOWED ON THE TAKEOFF ROLL, THE STUDENT PILOT ACCIDENTALLY ACTIVATED THE SPOILERS. AFTER LIFT-OFF, THE TOW PLANE COULD NOT GAIN SUFFICIENT ALTITUDE, WHILE TOWING THE GLIDER IN THIS CONFIGURATION, SO THE TOW PILOT RELEASED THE GLIDER AT AN ALTITUDE OF ABOUT 80 FEET ABOVE GROUND LEVEL. THE INSTRUCTOR PILOT TURNED THE GLIDER TO AVOID TREES AND ATTEMPTED TO LAND IN A CLEARING; HOWEVER, THE WING OF THE GLIDER CONTACTED THE GROUND. THE GLIDER THEN ROTATED ABOUT 90 DEGREES AND SLID TO A STOP WITH SUBSTANTIAL DAMAGE.