The certified flight instructor (CFI) reported that the accident flight was his first flight with the student. The CFI advised the student before the flight departed that he would be pilot-in-command if anything were to occur. He also briefed the student on the traffic pattern, air work that included slow-flight, and steep turns. They performed a preflight before takeoff, and no discrepancies were noted. With the student flying the airplane, the flight departed and remained in the traffic pattern; they were the only aircraft in the traffic pattern at the time. The airplane proceeded on the upwind leg, turned crosswind to downwind, and during the downwind leg the CFI advised the student that the aircraft was abeam the runway. When the flight was abeam the numbers, the student lowered the flaps to the first notch, reduced power, and then turned onto the base leg where he lowered the flaps to the second notch. The student pilot turned onto final and with a slight right crosswind, the student flared too high, and the CFI grabbed the controls and advised the student he had the controls. The CFI initiated a go-around by applying full power, but the student still had his hands on the controls. The airplane pitched up into a power-on stall. The aircraft banked to the left then impacted the ground. The CFI advised the student two times he had the controls. The CFI stated that there were no problems with the engine or the flight controls.