The certificated flight instructor and his student remained in the airport traffic pattern to practice several full-stop landings. While on approach, the student flared high and the airplane dropped 8 to 10 feet contacted the 3,375-foot-long by 50-foot-wide runway, and then bounced back into the air. While initiating a go-around, the airplane drifted left of the runway, and the airplane's left wing impacted trees. The airplane sustained substantial damage to the wing spar, and came to rest on the edge of the runway. Neither the flight instructor nor the student reported any mechanical failures or malfunctions of the airplane.