RAFAH, Gaza Strip, May 5 (Reuters) – By day, Awad al-Qiq was a respected science teacher and headmaster at a United Nations school in the Gaza Strip. By night, Palestinian militants say, he built rockets for Islamic Jihad. The Israeli air strike that killed the 33-year-old last week also laid bare his apparent double life and embarrassed a U.N. agency which has long had to rebuff Israeli accusations that it has aided and abetted guerrillas fighting the Jewish state.