The certificated flight instructor stated that during an instructional flight, he and his student departed a private grass strip on runway 22. They climbed to 800 feet and turned left toward the airport in order to simulate an engine out emergency. The instructor reduced the power and the student pilot turned back towards the grass strip to land on runway 4. During the final approach, the airplane encountered a tailwind, and in an attempt to go-around the airplane collided with trees at the end of the runway. Examination of the airplane revealed substantial damage to the firewall, fuselage, and wings. The pilots reported no mechanical deficiencies with the airplane. The nearest airport's weather observation system reported at the time of the accident; wind from 210 degrees at 6 knots.