The flight instructor stated that the instructional flight was the first flight on the second day of a five-day training program for the student pilot. The planned lesson for the flight included straight-and-level flight, turns, climbs, descents, and ground reference maneuvers. After completion of the maneuvers, the student pilot flew the traffic pattern for landing at the destination airport, and the flight controls were transferred to the flight instructor while the airplane was established on the final approach segment at 500 ft above ground level. Upon touchdown on the runway, the airplane bounced and turned sharply to the left. The flight instructor stated he attempted a go-around but was unable to increase airplane airspeed and regain airplane directional control. The flight instructor stated there was no mechanical malfunctions or failures that would have precluded normal airplane operation.