The pilot and flight instructor were conducting an instructional cross-country flight when the airplane lost all engine power. The airplane sustained substantial damage to both wings and fuselage during the forced landing into trees. Both wing fuel tanks remained intact, and no fuel was drained from either low point when sumped. The center fuselage drain point and firewall-mounted fuel strainers were actuated and produced about 1 tablespoon of fuel each. There were no observable indications of fuel leaking or fuel blight on nearby vegetation. The pilot reported that before the flight he fueled the airplane and estimated he had about 5 ½ hours of flight time. He stated that when planning for the cross-country flight he did not complete a detailed fuel burn calculation and that he did not use the pilot’s operating handbook to calculate fuel burn for the intended cruising altitude. The flight instructor stated that the pilot did not present a cross-country flight plan to him before the flight.