The sport pilot instructor reported that during the student pilot’s first dual instructional flight the engine quit while on a 1.5 mile final to land. The instructor made a forced landing on a dirt road during which the trike nosed over. Post accident examination of the trike revealed 1.2 gallons of fuel remained in the tank, which is at or below the empty markings of the fuel tank. The manufacturer reported that the unusable fuel level is 1.4 gallons. The aircraft was equipped with a fuel monitoring system that activates once the fuel level drops below 2.7 gallons. The pilot told witnesses that he had observed the low fuel warning on the instrument panel. The aircraft flight manual had a typographical error, which stated the unusable fuel was 0.4 gallons. As a result of this accident investigation the manufacturer corrected the error and reissued the corrected page to the aircraft flight manual.