On September 24, 2018, at 0957 eastern daylight time, a Cessna 172, N6950A, was substantially damaged when it was involved in an accident near Winter Haven, Florida. The student pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The student pilot stated that the accident flight was his third flight around the airport traffic pattern with his flight instructor observing from the ground. Each of the previous two takeoffs and landings were uneventful. During the third takeoff from runway 5, the acceleration and airspeed appeared normal during the climb, but after reaching about 300 ft above the ground, the airspeed began quickly decreasing from 60 knots to 50 knots. He declared an emergency, lowered the nose, and turned the airplane 180° to land on the runway. He reported he was “far down the runway” before he could get the airplane on the ground, and, once he landed, he could not stop the airplane within the remaining runway distance. The airplane continued off the runway and impacted a perimeter fence before coming to a stop. The student pilot reported that in the initial climb, “the plane started losing power;” however, he did not report any other anomalies or a loss of engine rpm. The instructor stated that the student was flying well during the previous two takeoffs and landings, but during the third takeoff, the airplane appeared to be at an excessively high angle of attack during the climb, and the airspeed was likely “bleeding off.” The airplane was directly over the runway when the student turned 180° even though “he had plenty of runway ahead of him.” After the accident, the instructor reviewed the accident flight with the student and during subsequent flight instruction, they performed a similar scenario to show the effects of airplane performance, situational awareness, and how to safely recover from excessive angle of attack. Photographs provided by a Federal Aviation Administration (FAA) inspector revealed that the left wing and windshield sustained substantial damage. The instructor, who was also the airplane owner, reported that during postaccident maintenance and repair, no mechanical irregularities were observed with the engine or airplane.