On May 21, 2005, about 1500 central daylight time, a Schweizer SGS 2-33A glider, N65855, piloted by a student pilot, sustained substantial damage on impact with trees and terrain during approach to runway 25 (3,300 feet by 50 feet) at the Beloit Airport, near Beloit Wisconsin. The solo instructional flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file. The pilot reported no injuries. The local flight originated about 1440. The pilot's accident report, in part, stated: The first flight of the day was an uneventful flight. This flight was a dual instruction flight with a one thousand foot tow (pattern tow). The second flight was a three thousand foot tow. No lift was found and the entire flight lasted about twenty minutes. On the way down I practiced coordinated turns. The concentration was outside the cockpit without looking at the instruments or yaw string. The second landing went well. The third flight (the accident flight) was also a three thousand foot tow. There was no lift so the flight was about twenty minutes. On the way back to earth I worked on speed control and speed control in the turns. At twelve hundred feet [above ground level] I was about two miles south of the midfield of runway seven. I turned north and did the landing checklist and tuned right to a left downwind for two five in the grass. I noticed I was [too] high so I add full dive brakes. When the runway numbers were under the left wing I noticed I was a little closer to better line of descent so I decreased the dive brakes to half. At about a quarter mile past the numbers I turned base and took out some more dive brakes. As I was turning final I noted I had very little dive brake left. I rolled wings level and noted that although not low I was much lower than I would like to be. I removed all dive brakes. With a headwind component of a little less than ten knots I will get most of the angle of decent back. I didn't analyze my glide path again. The prime focus of the approach now became the crab angle. I do remember wobbling back and forth on the runway centerline until I thought, for the second time, about knowing the winds. At about one hundred and fifty feet I noted that my glide slope had not improved much, I had a good ground track but I had a big slip nose left of center. The next thought was that I am trying to move up on the glide slope and I have a hard slip in my approach procedure. AND! I am slipping on the wrong side for these winds (wasn't true, I was slipping on the proper side for the winds just to much). It doesn't matter yet. Get rid of the slip before I am one foot off the ground where this will matter. Cognition of the rest of the control inputs is not consistent. Things started to happen fast. I released right rudder and immediately thought I was going to hit the trees. After this point time moved painfully slow, the only thing that was happening fast enough was the descent of the glider. he stick was off to the right but the wing wasn't coming up fast enough. As I am rolling through wings level to a right turn I notice that my elevation is higher than the treetops and if I don't stall maybe I can save this. I knew I had to ignore the trees and just fly the glider. As I continued the turn I recited "don't stall don't stall" over and over. The west side of the trees moved to my left and the north side of the trees was in front of me I rolled wings level and started to see grass past the trees. I started to think I could clear the trees. When wings leveled I looked at my glide path and could see I was going to hit the top of the last oak tree. The collision with the tip of the oak tree and the ground happened fast, both in the same second. Mistakes I made were a cause of the accident. The two biggest mistakes were believing the removal of the slip only mattered at or close to touchdown, and second, flying the approach by ignoring the trees and maintaining a distance clear of the trees by following the runway centerline. Another thing I need to work on is decreasing the number of instructors in my training. All of the instructors in my logbook are excellent pilots and [great] teachers. I think any one of them would have covered the information I needed to know to avoid this accident but without a coordinated curriculum to follow I may have missed something. The pilot reported no mechanical malfunctions in reference to the accident flight.